It depends on what you like to do, but here are my suggestions:
San Juan-Bacardi Factory, Old San Juan.
Catalina Island-Catamaran sail/snorkel.
St. Thomas-take a ferry to St. Johns and a cab to Trunk Bay. Trunk Bay is absolutely awesome. All the ammenities you will need, self-guided snorkel trail about 50 yards off shore, and the most beautiful beaches and water you'll ever see. If you'd rather stay on St. Thomas-Magen's Bay, Coki Beach, or Sapphire Beach are nice. Magen's and Coki have all the ammenities, Sapphire is more for snorkeling (if the wind isn't blowing too strong). Sapphire does have ammenities, but not as much as the other 2 beaches. There's also the tram, Blackbeard's Castle, and shopping.
Grand Turk-they're due to re-open shortly. We did some great snorkels there. I'm sure there was a lot of damage to the reefs from the hurricane, but the water and sea life is great. There's a nice beach area right by the pier and some shops there too. (At least there were before the hurricane). You've got a great itinerary and a great ship. Best wishes!