Who knows what style the missing valences were, but I bet they were basically boards held out from the wall (in front of the lights) on brackets. you could put anythign you want on the fronts of the boards - upholster them in cute fabric, tack on some driftwood, hot glue dozens of toy cars - pretty much anything. Just a couple small brackets, and a board (or two) long enough to span the fixtures, and you can take it form there!

Here's a tutorial for an upholstered version.

I suggest keeping it simple. The issue is that the lights are unappealing and you want to distract from the problem area, not draw attention to it. Recreate the concept of a valance simply by using a 1"x6" wood board, forget the upholstery. Paint it or stain it to match your existing trim. Think about it as a visual cover. You do not have to make boxes unless you want to direct the light to shine upward or downward. Use a large L bracket system to float the board in front of the light fixtures and keep the hardware hidden. It's a low cost, easy solution.

Make it a party!

I'm with getting rid of them too, but if you can't, I do like the 'board' idea but I might drill out holes or scroll some sort of design so the light shines through. That might be a really pretty effect.
Best of luck.

These lights, both the tube and the ballast, are being phased out of production. If you are renting get the landlord to replace them now. If not, consider replacing them now yourselves. Whatever you do, be careful about placing flammables close to any fixture.

Sorry, I work in facility maintenance so have to think about these things!

No useful comment, but Bayview is the best! My husband was raised there with his grandparents and the neighborhood has a great old Milwaukee blue collar feel.

You could cover them with blinds -- hang the blinds near the ceiling on brackets that will hold them over the lights (you can take the tubes out, too, so they are less bulky under there). Or suspend the blinds from the ceiling itself. I've seen this trick many times when people want to make an illusion of taller windows. The blind stops just below the top of the window and makes it look like the window extends up to the ceiling. Usually people layer some curtains at the sides of a treatment like this to keep the illusion going.

Just don't use the lights if you have something covering them/touching them! I doubt you want to use the fluorescent lighting anyhow.

I think "remove the fixtures" is the best solution, but am assuming that is not an option.

In some dressing rooms this kind of lighting is used. However, when a mirror is in front of it, it lets off a very desireable light. Or you could put painted (on the back side) plexi glass to give your room any color that you desire.

I agree with the simple wood treatment. You don't want to attract attention to these lights, so I wouldn't add any decorative elements. That said, buying the wood and building the covers and figuring out how to attach them will cost time and money, so you might want to estimate the cost first and decide if it would be worth it to replace them with something that doesn't suck.

MSchultz is right. The landlord is going to have to get rid of them eventually. If code doesn't force him/her to actually remove them, it will come down to the bulbs not being available. Do a little research and present the facts to your landlord and get them out of there. Save your time and money trying to find a fix. Spend your bucks on something you want and can move with you!

Google "cornice box" instead of "valance," and you'll eliminate a lot of the fabric treatments you don't want.

So I had something like this in my old apt--except they were vertical next to the mirror. My boyfriend came up with the idea to buy the screen that you use to make radiator covers (like they use here: http://www.thisoldhouse.com/toh/how-to/intro/0,,1582598,00.html). We make a template, cut the screen, and bent it into place. I used clear thread (like fishing line) and wove through the cut outs in the screen to secure them in. Worked like a charm!

Why can't you get rid of them? The light they cast is going to be ghastly anyway regardless of how you temper it, just take them down.

Colored plexiglass.

I would think of something like the decorative metal sheeting you can get from Home Depot – it's metal, lacey, perforated, comes in a lot of different colors. The simplest would be to get a piece cut out and attach it in front of the light.

http://www.homedepot.com/Tools-Hardware-Hardware-Fasteners-Metal-Stock-Sheet/h_d1/N-5yc1vZaqsp/h_d2/Navigation?

I'm having trouble understanding how there ever was a fabric valance on there, or even what I'm exactly looking at, but hope this is an idea for you!

I live in Bayview, and I love it! I don't have a suggestion for the lights, but welcome to the neighborhood. :)