If St John is a possibility and you really want to stay at a resort on the beach, check out Caneel Bay Resort. We stopped there and ate at ZoZo's one night and the grounds, views, and food were incredible. I think it's kinda pricey at $500-1000 a night... there are plenty of baller rental houses up on the hills for less though.
If you do end up staying there, definitely rent a Jeep so you can check out the rest of the island. Can't wait to go back...
Are you guys planning on snorkeling/diving or just laying on the beach?