Jake, the prices will depend a lot on when you will be cruising. I've been on the Adventure out of San Juan and loved it. Carnival may be less money the RCCL, you'll have to compare the differene on the cost. In my opinion, a group of 20 year old men would have more fun on Carnival or Royal Caribbean, than on Celebrity. You should also check out the restrictions on age. I think someone in your group will have to be over 21.