Thanks for the advice everyone!
Trip, I haven't been on the newest class of RCI but I have been on some of the bigger ones such as the Freedom. I've been on some of the smaller ships as well though. I'm not too worried about missing out on the newer, better things though. I know we'll still have fun.
Rirruto, I think we might need to check out Paradise Beach. I was researching beaches in Cozumel and that one came up many times. I'm sure we'll hit Senor Frogs or Carlos n Charlie's as well though.