I love CBR, its my favorite moderate and the rooms are pretty spacious (and larger than the other mods). I love the tropical theming and the new pool will just add to the overall pro's of that resort.
All that said, having an even larger room on the monorail with a daybed would be pretty nice. Although CBR is more centrally located so if the MK isn't your overall emphasis, CBR's location would be very good. Is really close to Epcot and MGM.
It's really hard to compare the two resorts, they are so different! But if you like things like interior corridors, room service, queen sized beds and a balcony, than CR would obvioulsy be the better choice. And probably why most people will steer you towards that resort! Just know that CBR is a lovely resort and the room size was fine for my family of four for our nine nights there in December of 2006.
I can't attest to the difference in a Garden Wing room vs. Tower room except that if they are larger and you have two daughters that age, extra space is never bad! I do have to say, I would miss the theming of the CBR, all the lush landscaping, the seven pools, the colorful villages and having a food court. But being walking distance to MK and having the daybed would be awfully nice.
If you go with CBR, they do have rollaways, I think they average out to around $17 a night. I generally take an airbed that has an electric pump when I stay at the mods. Its paid for itself many times over and during the day it can be propped up against the wall or shoved under the bed (as long as the bed isn't on a platform, CBR's beds were not the last time we stayed there).
In all you cannot make a bad choice!