Do your beach and downtown shopping during the day. Most downtown shops will close at no later than 6pm, some earlier. The Havensight shops may stay open as long as there is a ship in port. There are some nice restaurants and a few things like clubs around the island, but you need to be careful. By night there is a rather seedy side of St Thomas that emerges, especially in downtown Charlotte Amoile. The swell of tourists and cruise passengers is replaced by shuttterd shops, very quiet, almost scary streets and the "drugee" culture emerges on many of the street corners. Do not hesitate to find a restaurant or club, but, do not go "strolling" around town . It is , quite simply, not safe. Take a cab, wherever you go, door to door.
We stayed a couple of nights post cruise a few years back at a very famous local hotel.
Their restaurant had just closed and they were recommending several others to us.
When we said we would walk down to one, they would not let us. They called a cab, paid for it and arranged roundtrip transportation for us. Even the locals told us , walking around at night is simply not safe.