Well. First of all disney cruises are fun. I have been on 11 and enjoyed every single one. I meet people my age and lots more. If you like games and don't mind the price, the arcade on deck 9 midship is a cool place. If you don't want to pay, i just looked behind the game for arcade cards..
A second good place as tohers have stated is the stack. Many fun things up there, and you can meet a lot of people. Also, if you go on excersions you meet a family. Like me on the Med. Europe cruise. We met a family on a train on the way to Vatican city or something. I still talk to him in texts.
Back to the purpose, if you enjoy the cruises and disney places, a great idea would be to join the disney vacation club. It makes things a lot cheaper and seems more to enjoy all your vacations.
Another must see are the shows. You should know what times they are playing, what they are showing, and what theatre they're in. The main theatre for the shows are the Walt Disney Theatre. The movies are held in the Buena vista theatre.
Another great place to hang out is the lobby and such. On the third floor they have the large windows with seats. If you are bored or don't know what to do you could relax on one of those.
I hope my expierence will help you, and have a magical and Great cruise
