Hi B,
Just a quick thought regarding your ages. I know you said everyone was 21+, but (Jim, correct me here if I'm wrong), for each cabin, you'll need someone to be over the age of 25. I believe that's the rule for Carnival...not too sure about the age requirements for the other lines.
Just wanted to let you know about that so you can plan accordingly.
Have a great time!
Cathy in NYC