I also vote for the kiddie pool at the Yacht Club/Beach Club. Although we didn't use it (our kids are teens now), I thought it was very cute. I love the little slides they have on the back side of the ship!!
It seemed like a nice area for little ones to play in. We never saw big kids or adults (unless they were with a little one) in the area. The lifeguards also do an excellent job of keeping things under control at the pool complex.