Cruise would b nice..been to key west, cozumel n bahamas with group of 15 or so. You only pay for boat tix n airline. Meals are free, unless you get tired of buffets..they have restaurants. Only thing that cost $ is booze, but that's when you sneak on bottles of vodka thru water bottles like we did, soda is a fee..but u have one person buy a drink card. It's like $6 a day, but that's how you share it with everyone! Doesn't matter how many you order, as long as you have that drink sticker. There's excursions too as well whenever you dock at the destination you're heading. It can range from snorkeling, jet ski, Myan ruin tour..crap like that.
P.s we did like Cozumel better, water was super clear. And depending where u depart from you can make a day trip or whatever out of it as well. Since both times we departed from Miami, we spent a night there at this hotel called the starlite, next door to the "scarface" hotel. Was $60 a night but was across street from beach.. And prices are usually lil more during spring break.. But what isn't during that. Also planning another cruise, maybe we could turn it into a huge wisboard trip! Since you get price breaks after a certain booking.
Hope that helps, sry wrote too much. :/