All the values and mods have kiddie pools.
The rooms are bigger at the mods, but not huge.
CBR has the largest rooms. our room there was very clean, but that was a few years ago. CBR aslo has a kiddie play area.
All of the mods are pretty large to walk around, except POFQ. That might be a good choice for you. The pool there has a cute dragon theme. If your child is able to swim, then the water slide there is one of the tamest for small kids. (I'm picturing a 3 or 4 year old) The resort theming is good for little kids too.
We too liked CSR's pool, as adults. On the other hand, it is a convention resort, so you are likely to encounter drinking convention goers at the pool/hot tub area. Also, there is a big bar near the food court. I think it's been remodeled since we were there, but you could see the bar from the restaurant.