Leinster Bay and Salt Pond Bay are usually very calm, kid friendly with near shore snorkeling opportunities.

On St Thomas, if there is no heavy northerly ground swell, then the beach at Magens Bay is perfect. I see lots of kids on the beach with their boogie boards. Restaurant serves good burger, pizza and drinks. Brewers Bay beach is also very calm. Lindbergh Bay has jet skis for rent. They also have an enormous floating jungle gym - I'm guessing you pay some hourly rate to use it.