I've been to Grand Cayman, Tortola, St. Thomas and Mexico and Costa Rica and my experience was they were more prevalent in Costa Rica... having said that I did more activities that took place in more gator-friendly/croc-friendly environments, activities like a riverboat cruise in the rainforest, hiking along swamps in the forest and actually there was a big one on the beach (Pacific Ocean side) - the big croc usually hung out in a canal that fed right into the beach... he was a known to locals so at the time I really didn't feel scared because he didn't appear to venture on the beach... now looking back on it perhaps I should have been more scared
Grand Cayman - we just went to the beach and so no opportunities to see gators or crocs, craziest wildlife we saw were iguanas
Mexico - we were mostly on the resort so near the beach or the pool so we didn't feel nervous in mexico, the craziest wildlife we saw were stray cats...
My husband and I went on a tour of the everglades in 2004 and the guides basically said gators can live anywhere near a swamp, lake, water environment in a hot location... if you go somewhere on these destinations and see a swamp or a small lake or pond, steer clear, be vigilant and you should be fine