The US Virgins!! St. Thomas's Mahogany Run golf course (a George and Tom Fazio design) is one of the prettiest and most challenging in the Caribbean. The 13th, 14th, and 15th holes have been nicknamed the Devil's Triangle. Exciting! (This is where former President Clinton played when vacationing in St. Thomas). And the course recently finished a multi-million dollar renovation.
St. Thomas is a beautiful island. (You will, however, see poverty almost everywhere in the Caribbean -- except the Cayman Islands). I especially like the Virgins because they are mountainous with lush, green vegetation that falls down to gorgeous stretches of white sand beaches. The water is aquamarine, clear, and calm. Great snorkeling. And St. Thomas is ideally located in the midst of St. John and the British Virgins so that day trips (and even half-day trips) to several other islands is easy by ferry for a reasonable price. There are a number of excellent restaurants on the island and the best shopping port in the Caribbean.
If you go to St. Thomas, you must do a day trip to St. John (15-minute ferry). I think St. John is the prettiest island in the Caribbean with a picture perfect beach around every curve of the road, never crowded, and 3/4 of the island is national park.
And, depending on how long you have to spend...a 10-day trip, for example, could get you plenty of time on St. Thomas, St. John, and even Puerto Rico (a 15-min. flight). Although Puerto Rico's water is not as pretty (deep green as opposed to aquamarine from the many rivers that run off into the sea stirring up the water), there are many lovely stretches of beach and tons of stuff to do, including a multitude of excellent golf courses across the island, the only rainforest in the national park system, and lovely Old San Juan with its array of historic sites, boutiques, and wonderful restaurants. I always like to fly through San Juan and stay over for a few days in Old San Juan -- a real treat.
The added bonus, of course, is that you do not need passports for Puerto Rico or the US Virgins (you do if you plan to visit the British Virgins, however) and clearing customs is generally a breeze.