I've been to almost every country in the Caribbean, and each has its own qualities.
Puerto Rico: Nice transition from US to Caribbean, hotels and resorts are nice, but not exactly exotic.
Aruba: I love Aruba. Exotic, beautiful, tons of very nice resorts, fun and cool cities, very friendly people, easy to navigate and explore.
Dominican Rep: nice scenery, but underdeveloped
Cayman Islands: Quaint and pretty.
St. Thomas: very beautiful, but not a whole lot to do/facilities
Mexico: I've been to resorts in Ixtapa and Puerto Vallarta and have had a good time.
St. Kitts: very quiet, nice resorts, limited outside of that though.

I don't recommend:
Haiti (for obvious reasons)
St. Lucia: Too dangerous, underdevloped
Barbados: ugly
Grenada: beautiful, but no facilities


I also love Costa Rica, but it's more of an adventure place, but the beaches are somewhat remote (the good ones) and you can't swim most places.

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