As for a stroller ... I had the Valco Twin Runabout Stroller which I loved! I brought it on our 2008 trip (DD 1 1/2, DS 7 months) and summer 2009 trip ((DD 2 3/4, DS 1 3/4). For the 2008 trip, my dad had the folding down to an art and was in charge of carrying it on/off the bus. My mom and I were in charge of carrying the kids and bags. Summer 2009 I went with exDH and he couldn't be bothered learning to fold the stroller so I folded the stroller, carried the bags and a child, sometimes helping the other on/off the bus. This was unquestionably the most comfy stroller for the kids but the most bulky to fold.
In spring 2009, I purchased a
Peg Perego Aria Twin
Worked great! Lightweight, kids could recline, basket storage space for all my photography and tripod stuff. So why did I go back to the Valco a few months later? Well, a CM broke my stroller while moving it from its happy parking spot. I have no idea why or what he did but I saw him standing there with the side of my stroller and a

look on his face. Luckily, there were only 2 days left of the trip, but still ...
Last year I sold the Valco bc, at home, the kids are not in the stroller much at all. I purchased 2 single umbrella strollers (the generic type brand about $40 each, nothing fancy) which we took on a trial run to NYC during Christmas. One person could easily carry both & they fold up to practically nothing. I would park them in a central area, we would do the shows/attractions around there letting the kids walk and then when we would move on they knew to get in the stroller. If they napped, it was quick and in the stroller while in the park (I never went back to the room for naps)
This year I am contemplating what to do, my gut says take one since DD will be 5 and DS 4, but my mom is urging me to bring both.
So, that might not help much, but my experience in a rather long-winded nutshell!