RickG said:
Long Bay on Beef Island near the airport is protected from swells and has a nice grassy bay with turtles, rays, squid/cuttlefish, octopus, conch... We like the fringing reef at Brewers Bay. If you get a boat Monkey Point on Guana Island is well known, we also like Diamond Reef off Great Camenoe for drifting.

On VG, hit Spring Bay. The three bays you can walk from there, and swim to the Baths, are great fun. The outer reef at Mahoe Bay is cool when things are calm.

Tortola is a much bigger island than St. John and most of the beaches are exposed to north. Respect the swell and surf if it is up!

Cheers, RickG