I would definitely recommend either of the 2 water parks at Disney. They are so much more than a bunch of slides and a lazy river. The atmosphere is SO nice! At Typhoon Lagoon it is like being on a Tropical Island. We love cruise the Lazy river, sit at the edge of the water with our Mai Tai while DD plays in the waves in the wave pool. This year Slusher Gusher will be opening. They are hoping for a March debut. This is a water coaster and will have 3 different routes. Should have some pretty decent lines, as well! Most adults prefer Typhoon Lagoon to Blizzard Beach as it has more of a relaxing feel.
Blizzard Beach... pretend you are at a ski resort and it turned warm and all of the ice and snow turned to water. Now you have the picture of Blizzard Beach. All of the buildings are like ski lodges and ski rental shacks. They have a ski lift that will take you to the top of the mountain to ride the slides... There are some incredible slides here. Really appeals to preteens and teenagers. The lazy river is really nice, with great theming. The bobbing pool is like a wave pool, but never has big waves. You can grab an intertube and sit there bobbing away for hours.
Whichever one you choose, I don't think you will be at all disappointed in the waterparks at WDW! I have an annual WP pass and go there at least once a week once the temperature outside reaches 85... anything less, and I'd freeze!