Are you going on Legacy? Go back to the chat threads and read my multi part "story" of our trip in May . Also, search the Carnival threads for Legacy in late May and early June where I answered tons of questions.
You can walk to the shopping and historical sites in Old San Juan from the port (as long as the heat and a little hilly walking won't bother you). That is what I suggest for that stop.
St Thomas is a shopping port for most folks. We like to do beach and snorkelling as well. Maegens Bay is a beautiful beach but can get crowded. I recommend Coki Beach
which is next door to Coral World. There are facilities and food, nice "walkin" snorkelling
and you get a mix of locals and tourists on this beach. Many folks also take excursions to St John.
Time is limited on Tortola. There is not a lot to see in Roadtown. Get out and see the island. Take a cab to Cane Garden Bay, you will see much of the island on the way there and back. There are beach bars, and a number of places to eat along CGB and there is a distillery you can tour as well. Alternatively, take the ships tour to Virgin Gorda and The Baths. There is some walking down a path (and of course back up again), but the beach, snorkelling, rock exploring are worth the trip.
Please do not hesiate to ask any specific questions.
Donna, if you like to snorkel then i would suggest taking the water taxi from St. Thomas over to St. John island. Many beautiful beaches to choose from, Trunk Bay is the most popular- this one has a marked snorkel trail- can get crowded, we like Cinnamon Bay beach which is practically next door - less crowded, just a beautiful, good snorkeling. St. Thomas is a great place to shop- what we do is get over to St. John in the morning, come back to the ship around 1pm - grab some lunch, the serious shoppers will hit the shops either downtown or at Havensight, we like to leave time to take the skytram ride up to the top of the island, the view is breathtaking!
In San Juan is great to walk around Old San Juan, walk out to the fort. Kite flying is really popular out there, you get a view of the entire harbor from the fort. You can tour the rainforest - this will take up a huge chunk of your day. Barcardi plant tours are also very popular. San Juan has some very beautiful beaches also.
I had Windjammer on the brain when I said Legacy instead of Legend . One last tip,
the stern deck is the place to sit out. Nice pool and hot tub, near to ice cream and Lido deck food, and Wilmur the bar service waiter will remember your name and what you drink after you order from him once.
Have fun and be kind to MY ship.