Vanyran,
I hope you have a great trip. Your family will love Poly. We stayed there for the first time dec 2001. Our 9 month old (at the time) loved the pool and was able to crawl around in the "zero entry".
The water parade comes by at 9:00 each night and the kids will like that and the beach is a great place to view the MK fireworks.
The resort is lacking on a play scape for the kids, but does have a great water play space.
Have a great trip. Poly is a great place for people with babies.