Jebus,
I'm a travel agent and I could suggest a few places, however given how things are in today's economy I'd really suggest you take a cruise rather than a land vacation.
The cruise will be significantly cheaper, it will visit most if not all of those places and its got all the fun and entertainment on-board in 5 star style.
A typical 5 night stay in a 4 or 5 star all inclusive resort in mexico can run about $4k and thats without international airfare or transportation (land) costs. You could get it for a lot less but the 3 star all-inclusives are like staying in a motel 6 that has the Atlantis resort next to it (and you cant get in!).
Look up a 7 night or 8 night caribbean cruise out of Miami... in a balcony cabin (do NOT book anything but a balcony for honeymoon or you'll regret it.. she wont let you forget it lol ) ... depending on the time of the trip it could barely run you $2.5k