Why do most people choose the Caribbean to vacation?

I am looking for some recommendations on places to vacation in the Caribbean. I know there are a ton of islands to choose from but I would like some recommendations from people that have been there. I am looking for the following: 1. Nice beaches that aren't too crowded (will be going in June of this year) 2. A place that offers other activities besides hanging out at the beach. (i.e. hiking, biking, cultural activities) 3. Something that is geared more towards couples. Can u please help???