From my DD
Grand Turk - "I did the snorkel and stingray." She's done this twice and loved it.
St Thomas - I do Castaway Girl...that is where I got your t shirt and my long sleeve shirt. That is the best. The snorkling is probably better at other spots, but they are the most fun.
The long sleeve shirts are really nice - wish she had gotten me one instead of the short sleeve. Next time we are there I'll get her to get me one.
Puerto Rico - we did nothing.
HMC - she spent the morning at the beach and then came back to the ship for lunch although they do have a great BBQ on the island.
Because of mobility problems and because I've been there done that, I no longer get off the ship. I'm quite happy to spend the day at the pool - it's quiet and relaxing when most passengers are off the ship.
Hope this helps.