Hello RN75, and welcome to Cruise Reviews! I've been to most beaches and found Coki Beach in St. Thomas to be the best. We took my daughters family there and everyone had a great time. TripAdvisor has some reviews if you're interested.
Coki Beach - East End - Reviews of Coki Beach - TripAdvisor
There are usually two or three ships in port so you're going to see a lot of people where ever you go.