I vote Grand cayman also; been there 4 times and am about to go again ! Some very nice resturants and some low cost so you dont have to spend a bundle on food every meal ! Nice beach, can go snorkeling right on the beach in front of the hotel ! Use US dollars, very save walking even at night. I love it !
Don't try Grand Cayman unless you plan on spending no time in your room (which isn't a bad thing there) as the place is due for a renovation later this year. The location is great, staff is awesome and beach wonderful. Check out the reviews of the resort.
If you select Cayman change your U.S. dollars at the hotel and use Cayman dollars as you'll get a better exchange rate than at restaurants/bars etc., as your change will be in CI currency regardless.
Some of the very best resorts in the Caribbean are not near a city so you may want to expand your search.