Marriott Wailea has a nice water slide into a deep plunge pool. So if you like the Wailea area in general (we do), it is a reasonable option. We have stayed both in Wailea (Marriott) and Ka'anapali and liked the Wailea area better (less noisey and crowded). However, with pre-teen kids, the beach walk along Ka'anapali and Whaler's village is probably a significant plus. There are more interesting things to do in walking distance.

I haven't stayed at the Westin nor the Hyatt in Ka'anapali though I did walk by the Hyatt. The pool looked fairly elaborate though I didn't specifically look for slides. I haven't seen the pool at the Westin so can't comment on it.

--Jon