I've never been to Cuba, I'd love to try going once I get UK citizenship. I've been to the Caribbean in December and it was WONDERFUL! It was great to get a break in the middle of the dreary winter and have the tropical sunshine and warmth. In St. Croix, where I went, the beaches are empty if you're off the resorts because the locals all think it's too cold to swim. It's really just tourists on them. Me and the people I was with all still thought the water was like bathwater though. Must warmer than the water ever gets here in New England.
I love to see the way the locals live and try to experience the culture, so I'd do part on resort, part off if you have the chance.