We were very unimpressed by Tortola. However, to be fair, our booked excursion to see The Baths at Virgin Gorda, had been cancelled due to high swells. So that left us on our own to wander around the uninspiring port town. I'd like to go back and do an excursion next time.
We did a catamaran sail and snorkel excursion. It was a lovely day spent out on the boat, but the snorkeling left a lot to be desired. We made 2 snorkeling stops - one to see a coral reef and the other to see turtles. It was nice, but the water wasn't very clear and the scenery wasn't that interesting. The boat also made a stop at a beach for an hour. The crew was wonderful and it was fun just to be out in the sun.
We docked at the town of Pointe Pitre. It was a really grungy, scary town. We only wandered for 45 minutes or so before going back to the ship. The vendors were aggressive and it was very uncomfortable. Next time we go here, we will take an excursion.
St. Maarten is you typical, overrun island port. I think the best bet is to head over to the French side to Marigot or find a quiet beach area. The port area is nice, clean and modern with plenty of shopping. We had a great day, as we went to Maho Beach to watch the planes land. They are so close, you get blown over. It was really fun. Our friends went to Marigot and really enjoyed it. I have been to St. Maarten several times and always find great spots to visit away from the crowds.
St. Thomas is beautiful. We docked at Havensight and walked into the town. It was a Sunday, and all the vendors were going to close at 2pm, so the town was packed with shoppers. There is not much to buy there, other than jewelery. We looked for a place to have lunch, but didn't see many appealing options. We ended up stopping at a place closer to the ship, in a little yacht club / shopping area. There wasn't much to do here, but it was scenic and modern.
We actually stopped at the town of Ponce, Puerto Rico. It was a maiden call for Crystal. There was nothing to do there. The cruise only offered one excursion and even the shore excursion staff couldn't offer suggestions. The two options were to take a trolley to a promenade area or take a taxi to the town itself, where there is nothing more than a square. Ponce was the running joke with the crew for the rest of the cruise about horrible places to visit.
I've never found Key West particularly interesting. But as far as cruise ship ports go, I really like it because everything is close to the pier. The main downtown area offers interesting shops and places to eat. Stick to Duval Street and the downtown area (to the left of where the ship docks). If you go the other way, it is a little scary and ghetto. We enjoyed the day here. It was really crowded, and we were the only ship in town. I can't imagine how congested it gets with more than one ship.