How old are the teens? That will change things a lot. Some things that come to mind:
1) A resort in Miami. Something like the Lowes or something would have your nice pools, restaurants, activities, etc. while providing the benefit of having South Beach right down the street with its amazing culture, restaurants, etc.
2) Palm Desert, CA. Lots of great resorts out there, all inclusive types.
3) British Virgin Islands. Tortola or something like that.
A lot depends on how much you want to spend, too. Good luck!