These are all suggestions for St. Thomas....
In St Thomas you can take the "sky ride" to Paradise Point there is a great view up there and the ride is fairly close to the port - easy to walk to. There are quite a few shops there at the pier as well...although I'm not sure how good the prices are.
We've also taken the excursion over to St. Johns....Trunk Bay for some snorkeling. This was a lot of fun....rum or regular punch on the way there and on the way back with entertainment on the boat as well.
The excursion to Megan's Bay and Paradise Point was nice as well. Megan's Bay (I don't think I'm spelling that right) has beautiful white sand beaches and the water is gorgeous. We arrived fairly early in the day and had the beach to ourselves (the excursion group did) for an hour or so before other groups started arriving. About the time it started getting somewhat crowded we headed to Paradise Point where you can see in all directions at a great distance on a clear day. We still had time afterwards to shop by the pier.