The floor looks fine to me. I would love floors like that. That being said, hardwood painted white looks good.

Re-stain! Looks better, wears WAAAAYYYYYYY better. I've done both to hardwoods, and have found that stain is the superior option in the long run. Not that big of a deal to do, but definitely a bit time consuming. Go for a low voc water based stains and poly finish coat. The alkyds off-gas toxin for years and take months to cure out and stop smelling. Unfortunately, I've made that mistake before too! Good luck with it!

Seems to me that either method "painting or sanding" is a big job. I would go with the look that I want, rather than what appears to be the least amount of work. Can you get pals to help with the sanding and cleanup? Then you can stain and seal. A paint job after a couple of years may have chips and nicks but stain will last. Since you want to live there a long time, that might influence your decision. Good luck. Sounds like a great place to live.

Paint.

I would not suggest ripping out the flooring and putting something new down. Part of the unique charm of older buildings is the original features like hardwood floors, and crown molding/baseboards. I, personally, would sand them and re-stain them. Even though it's a lot of work the results will last forever, and you'll be keeping to the original design of the house. If you just can't deal with the sanding, paint is the only other option in my book.

Try a wood refresher first?? Something along the lines of a wood refresher. http://www.wocaoils.com/images/refresher.pdf this has information on one product. I used a Danish oil on a pretty crappy looking wood dresser and it really brought it back, I had considered painting it before trying the oil. All I had to do was a light sanding and apply, reapply, wipe off and wait a bit, and a final wipe down. Easy!
Good luck.

Whichever route you choose, I'd strongly suggest getting a professional floor refinisher in to do the sanding, if not the entire job. They'll have better equipment than you can rent, they should have some kind of dust control system, and they'll get the floor even with no sanding/burn marks. You may want them to fill the gaps too.

I redid the hardwood in my bedroom and spare room myself and I thought it was great, until it was time to redo the whole place and I hired it out. Huge difference! For the cost to drudgery ratio I won't do it myself again.

I would refinish (Have refinished mine that are 72 years old). You can rent a floor sander and have it sanded in a day. As for the stain/topcoat, make sure they are compatible. Most of the clearcoats that are made to stand up to floor traffic are oil-based and work only with oil-based stain. I have seen where a non-floor finish type poly was used and after only a few years of foot traffic, the floor looked very flat and dull.

Our floors were in similar shape when we moved into our 1920's colonial - they are red oak and hadn't been refinished in 30+ years and they had taken on a yellow/orange hue. We decided to have them refinished professionally before we move in, and its by far the best improvement we've had done for the money we've done so far. The floors were sanded down, and a mid-dark stain was applied with several coats of polyurathane (semi gloss applied). Old wood looks amazing when refinished, there's detail in the grain that isn't apparent in newer oak floors. And, refinishing helped with the "leveling" issue. The entire house (2,000 SF) was about 3k (in the Boston area), and the house just feels cleaner.

If you want to cut on expense, and you can live with the current color, screen sanding is an option, its much much cheaper (like half the cost). The top layer of poly is removed and additional poly is added. They will look shiny, new and clean, but you will be left with the same dark stain (which personally I like).

Get some well regarded floor refinishing contractors in for ideas and quotes.

As a side note, you can DYI and rent an orbital floor sander and do the job yourself, which my father recently did in his home, and save a lot of money. However, they are a little tricky to use.

BTW, I strongly caution you from painting those floors! The paint will seep in those cracks and there will be no going back (refinishing the floors later). And, paint doesn't always wear well (as I've seen in friends homes), and in the end you may be diminishing your homes resell value. Your floors are really charming the way they are, personally I'd live with them the ay they are if you aren't ready to make an investment refinishing.

I think they look fine, and are in pretty good shape. I think even just sanding off the poly and getting a new coat would look awesome.

Exactly what @jennysilentg said!

I had the same problem compounded by a total lack of cash and VERY bad allergies. As a temporary (5 years now) solution I opted to use a stain made from white vinegar and steel wool. My entire first floor cost me about $20. If you wish to try this first try it out on a inconspicuous section of floor to see how it 'takes'. Here's how it's made. Buy one gallon of white vinegar and a two gallon plastic bucket with lid. At the hardwear store buy a big package of fine steel wool. ( the finer it is the shorter time it takes to dissolve ) and WEIGH IT. You must weigh it as each package is different and trying to judge by volume is impossible. You must do this to keep the color consistant should you run out and need more. Pour your vinegar into the bucket and add the large package of steel wool, cover and fegeddabouddit for at least a week. Eventually, the wool will dissolve it the vinegar. This is your stain. Slop it on the floor like a bad mop job, let it soak in. After it dries your floor will be a dark brown/black.. Give it a week or so to really dry then tung oil or wax over it. Done. Cheap, easy and perfectly tolerable for anyone with chemical sensitivity issues.

Even if you painted, you'd probably need to do some sanding. My vote is to hire it out and do it right. I've gone the do-it-yourself route on a number of floors and they just don't hold up. It's not like painting walls.

Stain.

I would not paint it. I actually think this floor looks pretty good and patina of age is the best look for a floor. Just restore it. First pass would be removing all the dirt and grime with a rubbing alcohol and dish soap solution (1 cup alcohol per 1 gal water, 2 spoonfuls of dish soap).

Second would be a pass with Howard's Restor-a-finish or Tung oil - test and see which works better for you - it will depend on what's on there now. Resto-a-finish doesn't work over polyurethane but in that case I have had luck using Tung oil to fill in the worn areas. You can thin it with a little Gamsol (odorless mineral spirits available at art stores). Buff that out and apply again. These products have some off gassing, so be sure to get a lot of ventilation going and use very small amounts of product.

Last, if it's not polyurethane, I would do a pass with old fashioned paste wax (Howard's makes this too). If it is poly, then Mop n Glow that shit. I would not use that product every day, but to restore the poly, I might use it every 2-3 years.

Of course I would test this process first. I bet it will get your floors looking gorgeous and also old, which I would personally really value. So that's my opinion for what it's worth to you.

Whether you paint or stain, you need to sand first. Especially if the top coat is polyurethane. Staining isn't much more work than painting at that point. Only time I recommend paint is if the floor has damage and has been painted in the past or has only vinyl installation white glue that has sunk deep into the cracks and damaged areas and sanding will not remove it all.

If you go the ghetto route and just paint over the floor as is, you will have peeling paint everywhere.

I'd get some professional estimates and input. Get two or three floor refinishing experts in to look it over and tell you what THEY would do (and for how much!) At least then you will have a clue as to the salvageability of what you have. Whether you go with one of them or DIY will be your call, but since we can't tell much from photos, someone with knowledge on the scene can better advise you whether it's worth the effort to strip and stain.

I don't have a lot of faith in painting wood floors as a long-term choice. I have NEVER ONCE seen this done where it didn't chip and flake after a relatively short time. If shabby chic appeals to you, this might not be a concern, but for me it's a deal breaker -- I'd go with new flooring first.

its a rental....keep it simple! to be honest they are not horrid in any way. a nice area rug or some simple stenciling in a small area could make a big impact for minimal bucks.

Just be careful. With homes that age, who knows how many times they have been sanded and eventually, the wood DOES WEAR THIN.
I agree with most to keep the original wood and re-stain if possible. The last tentant probably stained it dark to cover up water stains or marks on the floor.

But I do agree if you paint, it will be very hard to go back.

I really like the idea @SherryBinNH suggested about getting some estimates to see what they would do, professionally, to the floor before you start your DIY.

Paint wear will be a lot more obvious than stain wear, so if you can, I'd restain the floors.

LEAVE THEM - they have character. That's my vote.

oh, i think they're lovely—they just need a little polishing up. i'd try a $12 bottle of bona high gloss floor polish before i did anything else.

Every time wood floors are sanded, you are getting closer and closer to the nails that are holding the boards down. At some point, you can't sand them anymore. I would only sand if they were particularly bad, splintery, etc. If your floors have an interesting patina, then anything you do on a day to day basis will only improve the patina. I personally would NOT sand, and only clean them really well. Then, you won't stress about people's shoes, dogs, chair legs scraping, etc. You'll enjoy your floor better.

Get them cleaned and polished first. That should be enough. It's an old building; let it have its patina. Painting the floors would not hold up as well in the long run and wouldn't provide the same warmth and depth that you have now.

If they're very old, and if there are very many layers of stuff on them, the floors may not stand up to sanding (it might wear them down to nothing). So be sure you know before you do anything like that.

since you wrote that many of your neighbours are artistic & have done cool stuff with their units- do they have similar floors? What have they done with them?

I think the floors are lovely as is as well - I would just do as others have said and clean them really well and use a scratch filler and polish them.

Don't paint. I live in a rental with painted floors, and after about a year, the paint started flaking. I'd much rather have very worn floors than floors with chunks of paint that flake when I step on certain spots or floors with scrapes where the doors open and close.

You have pretty floors, whichever route you take they will be interesting and stylish.I guess that's the beauty of hardwood. I have different had homes in which I have taken every path possible. Painting, sanding/staining with polyeurethane, sanding/sealing with poly, screening.
Painting is not as easy as you might think, I have done solid colors and large geometric patterns painted on old floors. In some ways, paint HIGHLIGHTS imperfections. The prep-work is time consuming, but rolling out the main areas is pretty easy. I loved the outcome at first, but after a little while the shiny finish dulled and dust and dirt seemed more noticeable.
I have torn up old floors and replaced with new hardwood. The floors seemed glaringly new compared to the other old features in the house, and not to mention, this is the priciest route.
You can have your floors "screened" this means the floor sanding machine is run over the floor and the top surface is roughed up. This is followed with two to three coats of polyeurethane. It is a good way to go if the floors are in good shape with only dullness and scuffing. You have to like your current color, this process does not take up the stain. Very inexpensive, even having a pro do it. I had three rooms, roughly 10x12 each, done for around $200. This is in the Chicago area.
Lastly, the full sand option. I have had the best results this way. My current house has a mid-tone brown stained wood, you can opt for no stain, natural is always beautiful. The darker stain does show a little more dust than a clear poly. But, overall, I have been happy with how it compliments decor and highlights interesting wood grains. Too dark a stain is VERY hard to keep looking good. (Looks like you might know about this with the walnut color.) I had most of my house sanded down to bare wood, and restained and sealed with two coats of poly for around $1300. Broken down, it is around $2 as square foot.
You can find small comapnies that can work inexpensively. It takes some legwork on your end to get estimates, but renting the machine and doing it yourself makes it VERY difficult to acheive eveness of finish and it is very time-consuming. I would reccomend going the professional route.
For affordability, I have worked in pieces in my home, as I can afford the cost and time. As I said, we had the majority done for $1300, this included the living room, dining room, sunroom, entry and upper hall. I had the bedrooms screened (the $200 mentioned is included in the $1300 total) and I just had my kitchen done for around $300 becuase I had the money at the same time we were away for a week.
One thing I have been unhappy with is the water-based poly that was used. There are pretty strict VOC regulations in Illinois, forcing floor professionals to use water based. I feel like I have had damage in some areas becasue it doesn't seal as well as oil-based poly. If you go the pro-route or DIY, try to get the oil-based poly.

Lastly, I just did my stair myself. Stripped, sanded, stained and sealed with two coats of poly. It was a TON of work and it looks just OK. For all my time and effort, I did not achieve the results I had hoped. I might still have a pro come and do it some day.

Lengthy I know, but hope this can help you. And good luck!

Please please don't paint them. There is no going back if you do and old wood floors are so charming. I think a good cleaning would do wonders, I wouldn't touch them otherwise!

We just had the line floors in our 100-year-old apartment lightly sanded, stained, then oiled with Waterlox (mix of tung oil and resins). Looks fantastic! And a big benefit is that if an area becomes worn, we can rub on a little more Waterlox and it'll look perfect -- try that with poly. Actually since I researched this, I see worn areas of poly everywhere, looks terrible! Even in super-high-end restaurants or shops and all the time in homes.

Great suggestions and tips from everyone, my wife and I will have to sit down and think about this. I know painting probably isn't such a good option now, I think staining is the way to go. I like the idea of having some professionals come in to take a look at it and give their suggestions on how they'd do it. At $2 -$2.50 a square foot to refinish the floor, I don't think we can afford it as we have approx 800 sq feet to redo. I don't mind doing a lot of the work though myself if I know it will turn out good. I did book off a week from work for this, so maybe between now and then we can do lots of research before attempting any work on the floor.

Thanks for everyone's suggestions, tips and ideas, I think staining is the way to go.

I put off having my hardwood floors refinished professionally because I thought it would cost a fortune. When I finally got an estimate, I could have kicked myself for waiting. It was far less expensive than I had expected. Call several professionals, discuss refinishing vs. painting and get estimates. Even if you decide to do it yourself, you will have received some expert advice.

@Hilton- your steel wool and vinegar stain sounds interesting. Did you sand your floors to do this and what is the sq ft of the room you did? I really would like to try it in my bedroom.