Here are just a few that have gotten good reviews before, with at least one waterslide (large or small), some with a waterfall or fountain as well:
--- Gaylord Palms
--- Marriott Orlando World Center (and the timeshare villas on their grounds - Royal Palms, Sabal Palms, Imperial Palms).
--- Hard Rock Hotel (at Universal)
--- Caribe Royale All-Suites Resort
--- Ron Jon/Isle of Bali (nice for kids under age 10)
--- Sheraton Safari Hotel
--- Radisson Parkway
--- Marriott Horizons Resort
--- Orange Lake Country Club
--- Sheraton Vistana Resort
--- Sunterra Cypress Pointe
If the slide doesn't matter to you, then the resorts with lovely pool areas, including waterfalls/fountains and hot tubs/kiddie pools are numerous!!! For starters, try these additional timeshare resorts:
--- HGVC Hilton Grand Vacations Club
--- Sheraton Vistana Villages
--- Marriott Grande Vista or Cypress Harbour Resorts
--- Star Island Resort
And of course, there's always the Disney moderate and deluxe resorts.

Hope that helps!