Cane Garden Bay
The North Coast is where most of the great beaches reside:
Cane Garden Bay: A long strand of white sand along the Northwest coast. This is the most popular and busy beach and has plenty of watersports facilities, restaurants, and bars. It's a great evening location as well.
Apple Bay Beach and Long Bay are together with a big hill separating the two. Apple Bay is pretty and has many vacation rentals and two hotels (Sebastian's). Bomba's Surfside Shack, a great nightlife place, sits along Apple Bay. Bomba's has a popular "Full Moon Party" on the beach at night every Friday around the full moon. Over on Long Bay, the Long Bay Beach Club dominates a very nice, calm beach.
Smugglers Cove sits along the western end of Tortola. This clear and calm stretch of beach also has good snorkeling. It's harder to get to - wear your shoes rather than sandals - but is usually very quiet. The houses of Belmont Estates are near here.
Elizabeth Beach on the eastern end, facing Anegada is a more natural, wild state beach.
Lambert Bay along the north shore is another decent spot. Probably the prettiest for sunsets.
Lormier, Cooper, Trunk and Josiah's are all along the northeast part of the island, near Lambert and facing Guana Island. This is a good group of beaches to attempt to visit all in one day.
Snorkeling? Head to Brewer's Bay. Smuggler's Cove, Cane Garden Bay, and Brewer's Bay
Long Bay, on Beef Island, near the airport is great as well, though not easy to get to from the West End. There are some houses along the east side, but the western end is very quiet and tranquil. Perfect for walking because it's almost a mile long.