That all depends on what you want to do. If you want to relax and recoup the Caribbean is great. I know it's probably the most standard vacation but that's for good reason. It's one of the best.
If adventure is more your thing, check out Argentina. It's such a unique place and so much different from the modern world. Many amazing sights: Andes Mountains, Perito Moreno glacier, Tierra Del Fuego, just to name a few. I've written a hub about it if you're interested.