There were party animals at our second week in Feb bash. Couples and singles, in all age groups. NO ONE was too grown up, not even me, and I'm 65. I don't think it attracts (or at least retains) people who aren't pretty loose about life. If you're looking for a standard package, you ain't gonna find it there, baby.
I think having all the divers brings a complete mix in age and attachment. If you're young, you'll find lots like you runnin' around the beach and the dance club.
I don't know about the mainland stuff, but the Caye is really everybody except people looking to be taken care of in a big resort with all amenities and a big hotel facade.
You'll love it.
Michael (the Monster)