Having stayed at ASMo, CS and POR, I would think your kids may like ASMO or CS better than POR. As another poster mentioned, CS has a great themed pool and play area that is rather central and easily accessible. While I love POR and hope to stay there again, the resort screamed "Romantic Adult Retreat!!!" to me with its winding pathways and quiet nooks that are easy to get lost in. I can imagine very young children getting tired of having to cross bridges to get to the pool. However, if you want a bit of romance with your wife, POR might be the best bet.
As for bus service and long waits, I encountered the opposite problem - huge lines and waits for buses at CS and minimal waits at POR. But bus service can be a very hit-or-miss thing at best, so I wouldn't have it be a major factor in your decision.
The AS resorts have TINY rooms. I don't know if they would allow you to get only 1 room but even if you could, it may be a very tight fit. But I agree that for your children, the ASMo might be the best bet due to the characters. Where else do you see a giant Buzz Lightyear and get to stay in the Fantasia building?
Kat