The Omni International Hotel has a great pool area. Not only does it have a water slide but also a lazy river. It is great fun, we stayed there this summer and would not hesitate to stay again. We got a Travelzoo rate of $99.
The Nick Jr. hotel has an awesome pool (two actually) with amazing waterslides.....however, there rates are high.....perhaps you could swing it though because it is only for one night.
Teresa