All your typical travel sites like Expedia, Orbitz, etc will have vacation packages. Decent starting point.

Most of my experience with them was when I was a kid, my family went to a few all-inclusive resorts. All the kids like 13-16 would be cooped up in the resort but would usually get served booze so lots of shenanigans.

Like others have said you basically bum around the resort and eat and drink yourself silly. You can also sign up for other activities out of the resort but those cost extra. So as long as your main goal is to be somewhere warm with nothing much to do it works pretty great.