Ditch the stroller. Get an Ergo Baby Carrier. http://www.ergobabycarrier.com/
We used ours with our daughter until she was 3 years old. It was much easier for traveling than hauling a stroller around. It's really comfortable and it packs up small.

While I totally respect those who can carry a child around all the time, it's not so easy for everyone to do it.

I say rent a stroller when you get where you're going, that way you don't have to worry about checking your stroller and you can use what you need while you're there and get home and have what works for you where you live - without having to buy something new for a short period of time.

There are company who rent strollers, high chairs, cribs, pack and plays and other baby supplies all over the country. We used Baby's away when we traveled. It's an added expense but cheaper than buying something new.

If you do want to buy something, I'd definitely check out craigslist for whatever stroller you find rather than buying a new stroller and then resell once you're finished with it. You might even be able to find an item on craigslist where you're traveling to that you can pick up when you get there. ;)

I was going to suggest renting as well. I live in a resort area and all the bike shops rent jogging strollers of one sort or another.

Or maybe scout out a used one on Craig's List in the area you are traveling too and then donate it to a thrift store before you return home?

Ergo is great!! We live in Seattle and have been to the San Juans often. This baby carrier works great for us and it will even hold a toddler comfortably if needed (our son is 3 1/2 and I can still cary him).

San Juans are not a great place to rent a stroller. If you MUST buy one - consider the BOB revolution - http://www.bobgear.com/?gclid=CMSn14mEk6kCFcYbQgodtSdDqQ. We also have it and find it very off-road friendly. It is not cheap, so consider Craiglist. If you have to buy it new, it does retain good resale value.

Borrow/rent a kid backpack. It will be a smoother "ride" than any stroller on the trail. Make sure you adjust the straps so that it fits well.

If you're flying into Seattle you can rent there
http://new.happylittletraveler.com/products.html
Not that I live there though so the wseattlemom probably knows more & I just looked quickly. They do have the BOB Revolution though.

I've tried to take our Bob on hiking trails... and it really didn't do so well. Jogging on rough roads, not smooth walking trails... LOVE it. Hiking trails? The back pack is a much better option, especially if you kid isn't super big. My 3 year old is at the 90th percentile and so wouldn't so so well... or should I say, I wouldn't do so well. But, places like REI have some really great kid carrying back packs that make it feel like your just carrying a normal pack (OK, one that kicks and puts cracker crumbs in your hair) - that would be what I would do. Ergo is more for around the house stuff... not the trail.

Thanks for the suggestions! My son is 3-1/2 and grew out of his Ergo long ago (or rather he refuses to use it anymore!)... so that's out of the question.

I'm going to look into happylittletraveler.com rentals. What a great idea!

Thanks again!!

Another Seattle mom, and I would recommend the Baby Jogger City Mini - it's our only stroller, and works great for city, parks/light hiking, and collapses perfectly for travel - ours has been everywhere, and works great!

I live in the Seattle area. We love hiking and are very familiar with the San Juan Islands. Will you be visiting all of the islands or only one in particular?

If you plan on hiking unpaved trails I would definitely suggest a carrier of some sort. Strollers (even our Chariot) do not maneuver well on Pacific Northwest trails due to the terrain and foliage growth. You will find that your adventures may be limited with a stroller, and may find a carrier of some sort to work better for you.
We have a Beco, which is similar to the Ergo, which we love. It seems your son does not like his Ergo, in which case a different carrier may work better for you. Kelty, Deuter, etc.

Whether you buy or rent, my suggestion would be to find a carrier that works for you and your boy instead of relying on a stroller.

If you find a stroller that fits that description, then please let us know. I think it's a mythical beast. We searched extensively for the same thing.

I was going to also recommend the Baby Jogger City Mini as the closest fit. It's wheels are larger than a standard stroller (but not pneumatic, on shock absorbers, or as large as a true jogging/all-terrain stoller) and folds beautifully. It’s truly a one-handed fold/unfold and fairly lightweight for a stroller its size. Plus, the sunshade and rain cover are excellent. It's great for uneven sidewalks, cobblestone, curbs, gravel, etc, but I wouldn't take it through a muddy or tree-root-heavy trail. We have the city mini and a jogging stroller, and we've used a friend's BOB. The BOB is definitely superior for rough terrain, but like a previous poster said, it's still not perfect. And those suckers do not pack small, even if you're willing to pop off the front tire.

Lightweight + all-terrain seems like a pretty impossible combination to me. We're going on vacation this fall when my son will be 20 months old and we're buying a Kelty external frame pack to carry him. I think the Ergo and other soft sided carriers are great, but with my 75th percentile son, they're already not that comfortable to wear for extended periods.

We hiked Yosemite with our one year-old using a kelty external frame pack. It was very comfortable for both myself and my husband and I highly recommend it. The pack gave our daughter a great view of everything and she loved it. I definitely recommend checking into that and trying one on. If you have an REI near you should be able to test it out there. That's where we got ours several years ago.

I use my Micralite fastfold. It is like a "bugaboo" in an umbrella stroller form. And when collapsed, it stands upright unassisted.

I love our Mountain Buggy Swift - we live in Australia & have travelled with it easily throughout Europe & America (including "off road" & cobblestones). It's the most compact of the Mountain Buggy range & was about $700 over here but probably cheaper on your side of the ocean. Collapses easily & is very sturdy - have no complaints after 2 years.

One obvious tip for any stroller with air-filled tires is absolutely keep the pump with you at all times because roughing it can make them lose pressure when you need it most!

Sorry, meant to include a link for the Swift - http://shop.mountainbuggy.com/buggies/single/swift-stroller

Baby Jogger City Mini - super lightweight, EASIEST stroller to fold and great for traveling. It's also our only stroller. I take it to the dog park and go over the grass, dirt and mulch pretty easily. But if it's heavy duty hiking you're talking about, I'm not sure I would use a stroller...of course I'm picturing hiking in the foothills of Pasadena (like Eaton Canyon) where I grew up and I can't imagine pushing a stroller up those hiking trails :-)

Are you sure you'll even need a stroller for hikes? You know your child best, but I know that my son would want to be out of a stroller as much as possible. 3 1/2 is when he stopped using a stroller altogether, so if that's the case with your son, trying to rent one just in case is probably the best/most economical idea. Have a fun trip!

I love our Mountain Buggy Terrain! We pushed DD up a number of mountain trails in the Rockies when she was about 3 months old and it was great. We've probably flown with it more than 30 times and it's in great condition (gate checked every time). DD is now 4 years old and we just took it to Costa Rica and hiked around the rain forest and it was perfect. We went on one hike with a family that also had a 4 year old and it was a HOT day and the child was miserable - hot, exhausted and just wanted to be carried, making the family miserable. They were super envious of our stroller.

I know some people are against strollers, but trust me DD gets lots of exercise but the stroller gives us so much freedom for exploring and taking on bigger adventures than she could ever handle walking!

I forgot about the Kelty. It's a great option if you kid likes to be up high and will stay put for a bit. Since he's 3 1/2, you might check the weight specifications.

If you can't find a Kelty to rent, you could borrow ours. It has a sunshield and a day pack and is in great condition. We didn't use it much because our son preferred the Ergo (and he's small for his age).

Awww, let the little guy walk :) Put one of those tiny Camelbak's on him to make him feel like a big hiker, pick super short routes, settle for the awesomely slow pace, and take lots of breaks. Even if you just go a quarter mile, you'll experience it so much differently at his pace. (but maybe have your Ergo on hand as a back-up!)

If you do bring a backpack make sure you take it for lots of trial runs to build up your back muscles. Toddlers get heavy no matter how ergonomically designed the backpack.

Whether you get a backback or stroller, remember you can always sell it later.

The advantage of a stroller or backpack is that you use them to get TO better places to let your little one explore, rather than just the beaten down, overused first 100 metres of the trail head :)

We bought a Kelty external frame backpack off of craigslist and have used it for a couple of short day hikes. However, we've found that slow hiking with breaks suits our 2 year old much better than being carried. Yes, it limits your distances, but even our luxury jogging stroller can't handle real trail hiking.

I second the Mountain Buggy Swift suggestion. It's a fantastic durable little stroller. It is only 21 lbs and can hold a child up to 70 lbs. It doesn't have rear suspension, but will still be able to stand up to the trails you are looking to take it on. Plus, it has a much more narrow profile than most of the other strollers in its class and will likely be a bit more maneuverable because of it. Give it a look!

We had a Kelty backpack for a while and both my husband and I thought it was uncomfortable. As another commenter said, a toddler is heavy no matter what. If yours is too big for the Ergo I'm guessing a frame pack will also be uncomfortable for you.

An all-terrain, lightweight, collapsible stroller definitely is a myth. :) But City Mini seems like it tries the hardest to reach a workable level of all three. I think for a really good stroller you have to give up at least one of those requirements. We really liked our BOB Duallie but it was too heavy for me to lug in and out of the car, so I sold it and went with a Phil & Teds Sport instead, which is not as heavy duty but folds up more easily and is more lightweight. The City Mini is even less heavy duty but folds up even more easily and is even more lightweight. I guess it depends on what you value most.

I would say to let the kid walk on the really rugged trails, and use a stroller for the more paved areas. If he really gets tired he can ride on someone's shoulders, right? (to me that's about as comfortable as a Kelty pack!!)

If the Ergo is a no-go, you also might look into a Boba. It's designed for a toddler, so might work better.

I'm all for walking too. I just did a very rugid trail in california with 2 three year olds, and they were champs, and walked the entire trail, just loving it.