Hi, Vicki!
I've taken a 12-15 on NCL--depends on the ship and itinerary. Everyone I've taken has been good experience--they do a good job with service. I've also used RCCL and they are a cut above NCL but less freestyle.
I'm personally not fond of W. Carib--you can get great all-inclusives in Riviera Maya w/car rental from CUN and see the ruins yourself or with local guide.
The port there is newly manufactured for tourists--kinda sad to go so low. There are more options for Easter Carib--assorted islands with more "lushness" (that's foliage, not alcohol!! hahaha) Jamaica thrills me not and Key West may as well be Maimi--all the private island stopovers are pretty dull--just a way to get you to buy more fancy drinks in fancy cups and get drunk on the beach.
The exotic cruises leave from San Juan PR. Princess is very fine line--upscale from RCCL. Carnival is just what it implies--some of the megaships are supposed to be oodles of fun, but that's too many people for me. (my best friend is trav agent and has taken nearly all of the lines, so I'm using her opinion for lines I haven't cruised)
I've booked with Dargal and Perx--fave is interlinetravel.com. All websites have some real steals for last minute, too.
Good luck--hope that helps