I've spent a lot of time in Wailea and it's easily the nicest resort in that particular area. The Wailea Grand has lovely grounds (as does the Fairmont), but I believe the rooms are much nicer at the Fairmont. Regarding the resorts at Kaanapali, I think the resorts there are certainly no nicer, and the quiet and solitude of Wailea (and the slightly nicer weather on average, due to its more southern location) make it dominate in my books.