P.S. When in St. Thomas.. You must visit Megan's Bay. I actually have a card from the Taxi Driver who took us on a tour of St.Thomas and dropped us off at MB..
We tend to not book excursions via the cruise ships because right outside the gates you can get the same exact excursions for a lot less money. Many people will talk about how "not good" doing that can turn out to be but I've never had any problems. Many times i'm on excursions with people from the ship and the only difference is, they've paid more.