Please note: BOB JUST came out with new, updated version of its stroller for the FIRST time. They do not appear to have made too many significant changes, but this review is of the old version.
We purchased the BOB Revolution Duallie (their double side by side) and used it for a good six months. We live in the city and the stroller for us is like our car. We take it everwhere. My children are just under two and a half years apart and my older child is very much a stroller child. That being said, now knowing that the Buggy Board (see next post) works with the BOB - even though I don't think it's recommended, I might have forgone the purchase of a double stroller altogether - strictly because of storage issues (and price - though ours was a gift from generous grandparents). We didn't use it much in the dead of winter b/c the sidewalks were much narrower with the mounds of snow. I have just started using it again primarily for playground and park visits, and I realize how much I still love it. If you do run/walk with your children for exercise on a regular basis, I'd imagine the double would be that much more important, and the double BOB, like the single, handles like a dream.
Double stroller thoughts...People do love the Phil and Teds front and back double as well. It's not quite as maneuverable as the BOB, but it's a good work horse. My husband was very opposed to one child in front of the other "blocking their view" and potential fights about the front/back seat, and little hands have been known to get caught in the wheels (they provide shields for the wheels now), so we didn't do it. There are other newer additions to the double category, including the City Select Double. I did a ton of research and we actually purchased this one first and had it for about a month before deciding it was much too difficult (for me) to drive with both children in it. The configuration was front and back and had a million different possible arrangements which made it a very exciting purchase, but I could not maneuver it well with both children. We do see plenty on the streets and have read great reviews, so it may have been me. There continue to be new strollers introduced in this category, including the new Bugaboo Donkey and the Britax B-Ready. The Uppa Baby Vista continues to be a strong contender as well. I might have considered that one if we had had it as a single. The Citi Mini single and double are also very popular in the city. Less frequently I see double Maclarens and other umbrellas, but I imagine they're more popular out of the city. There are also the sit and stand models like Joovi Baby, and super high end imports like iCandy. The list is nearly endless.
To date, I haven't heard of a double that doesn't have some issue (width, length, maneuverability, seat positions, folding, etc.). At the moment, we are most often using our single BOB and Maclaren with the Buggy Board, and/or with our nine month old in the Ergo.