If you'll use your "Find" feature in the upper left hand corner, type in Grand Turk, it will pull up all the posts made. When we were there, we did a snorkel trip. It made 2 stops, one for coral and one for sea life. The water was crystal clear and the snorkels were great. There's a shopping area right at the pier and a nice beach area there as well (at least before the hurricane there was). Hope this helps.
We did a feed the stingrays / snorkle excursion which was neat. We also took a cab into town to walk around a bit. There is a small musuem which we did not visit because we felt it was too expensive ($10 per person, if I remember correctly). The town is small, but we had a lively visit with a man in the visitor's / tourist office and with an elderly man working in a store, who gave us a brief recent history of his home. The island is small - you can rent a car or a taxi/bus or do a ship's excursion around the island to visit the lighthouse and the salt flats. It is/was a lovely little island, which I heard got hit badly by one of this summer's hurricanes... so it is hard to say how the beach or snorkling will be. Although, if you dive, it's said to have some of the best diving in the Caribbean. There is also a Margarittaville at the Cruise Center which has a pool and there is a beach setup right by the pier for ship's passengers.