I've been to the Caribbean 4 times and hope to go again before the end of winter. Its been a tough especially for you all on the East Coast. Hope to see you there!
Heres' my picks for Best Caribbean Beaches:
Virgin Islands -St John
Cinnamon Bay
British Virgin Islands: Cane Garden Bay
Antigua: D ickenson Bay and Half Moon Bay
St. Maarten/
St Martin: Dawn Beach and Maho Bay Beach
Trunk Bay (St. John) but lots cruise-ship passengers! it's known for its underwater snorkeling trail.
Anguilla - Little Bay Beach. To reach this cove, you'll need to hire a boat or climb down 66 feet on the fishnet ladder tied to the bluff's top.
St. John - Any beach on Caneel Bay