In St. Thomas we did the 5-Star St. John + Trunk Bay excursion. This is a fabulous trip in an oyster boat around the islands to St. John where you snorkel a reef and and/or swim off Trunk Bay (gorgeous). Still had time to take the Skyride to Paradise Point when we returned. In St. Maarten, we did the See-N-Sea. That's a bus ride around both sides of the island with a semi-sub ride on the French side and a visit to Marigot (French capital). Whatever you do, don't miss seeing both sides of this island. The Dutch side where you dock is nice but too commercial for me (casinos, fast-food). The French side is very quaint and scenic. BTW, fabulous cruise, you're gonna love St. Thomas/St. Maarten.