Hi S.,
I am also the proud mom of two under two!! Congratulations. My oldest is almost two and my youngest is 13 months younger, so I know all the issues with doubles. With my fist son, we used the Bob Revolution, which I loved, so I looked long and hard at the dualie. However, I felt that their double lost a lot of its everyday functionality (i.e., its ability to maneuver in tight spaces) that I so loved about the single. So, I looked and looked, until I found the greatest double stroller of all time: The Phil and Ted's E3 Explorer, with the doubles kit.
Check out baby gaga for reviews: http://strollers.baby-gaga.com/phil-and-teds-e3-explorer.php
My take is that this thing is just so darned adaptable. When my youngest was a newborn, he could lie flat while my oldest sat in the front on the removable seat. Once my youngest could hold up his head and wanted to sit up during a walk, we just moved the removable seat to the back and he is now the "goose" to my oldest's "maverick." You can fit through any doorway and you can still lock the front wheel if you want. Everywhere we go people comment on how cool this stroller is, and they often miss seeing my youngest in the back! We had a Peg Perego infant seat (which was so great, despite being a little heavy) and both the Bob Revolution (double or no) and the E3 accommodate this seat.
The other thing to consider is a stroller platform. I know that my almost two year old still wants to sit in the stroller sometimes, but I clearly see the day where he will not want to sit strapped in at all. But, we all know they still get tired and can't walk as far as they may want to, so voila! the stroller platform:
http://www.babyearth.com/lascal-kiddyboard-maxi-stroller-...
Just make sure it fits your stroller! Good luck!