I have a big almost 4 year old and a 9 month old. I agonized for months before #2 was bornm, as to which double stroller to get, especially because of the weight maximums for a lot of strollers, some only go up to 40 lbs/seat, which my older was at already, plus we were limited also because we had a Chicco infant carrier, and needed something with an adapter for it. We finally settled between the BOB duallie and the City mini baby jogger. The BOB was roomier and therefore wider, and my husband hated it when we tried it out in the store, so we got the City Mini with an adapter. The adapter took a while to set up (though probably we were sleep depreived at the time, it arrived the day after we came home from the hospital, #2 was 3 weeks early) and didn't seem like it clicked properly, it even has some straps to put around the infant carrier, but it worked, and we had no problem going to the zoo and parks and places like that, plus it's fit thru every doorway so far. We got a great deal at Amazon, it was a 2011 for the same price as the 2010 model, and gave us a whole year of amazon Prime, (had already signed up for Amazon Mom, now they are changing things, I think starting today, and you can only get 3 months of Amazon Prime) plus, since it was part of my amazon baby registry, we got an extra 10 or 15% off, can't remember the exact #. The only thing I don't like is that the space is very limited for storage, there is a bar that divides the basket in 2, so big diaper bags don't fit, but we use a hook. Also, and this is almost across the board, you end up having to buy extra everything for it, most strollers come with nothing, no cup holders for parents or kids, so we had to buy a belly bar and then bought the cup holders for us and the kids from Sunshine Kids, now I think they changed their name to Diono or something, for $8-10 dollars each instead of over $20 from the jogger brand.
At any rate, that is what has worked for us, but each situation is different. I would recommend getting something with a 50 lb per seat capacity, since it's an investment, and you might as well get to use it for a long time. As someone mentioned, there are also the sit and stands, but that even now won't work for us, my older one would never stay in the stroller that way, and it's not as comfortable, nor really useful in the winter, for example, since I see U R in NY. One thing I found useful in my search, was seeing online reviews, can't remember her name, but there is a lady that has a ton of online reviews and grades a ton of single and double strollers, shows how to open and close them, and gives all the pros and cons. I think that I found her on a video review on Amazon for the city mini jogger and from there you can go to her page and check all the reviews. Good luck!