St. John has some great snorkeling and diving, too, if you enjoy that sort of thing. St. Thomas isn't bad for shopping. (BTW, you can find those tasty tinned rum cakes all over the place, and they're worth bringing back at least one.)
As for St. Maarten....it was okay. When I was there it was late January and there was fresh snow -- a LOT of fresh snow
-- at home on my mountain and I was just happy to be in the sunny-and-warm for a change. Not that I think Disney would plan an excursion near one (at least not intentionally), but just so you know: there ARE clothing-optional beaches there.
The beach I was sent to for my shore excursion had kids building sand castles as well as folks walking around starkers, and no one seemed to care about any of it.