Magens Bay is deemed the #1 beach on St Thomas and is always a great day.  This beach has a good snack bar, a beach bar, restrooms, showers and a gift shop in case you forget anything.  Check the cruise ship schedule online as it can be crowed between 11 and 3 if more than 3 ships are in port.

Magens Bay - Picture Yourself There:

Magens Bay is long. Here is the view during the walk along the empty beach: