No matter which line you choose, you need to make sure that you guys can sail on them because of age restrictions. Ask your travel agent to be sure.

If anybody is under 21 on the day the ship sails (even if their birthday is the next day), many lines won't let them go without a parent or guardian. Some lines won't let unmarried people under 25 share a cabin, things like that. It's not a huge hassle as long as you check before and don't be surprised at the dock.

Carnival probably makes the most sense, it's a younger crowd, certainly more of a party crowd then the other ships, and I believe over 21 they don't care.

Couple things to remember, it's the total cost hat matters, so when you are planning think of the travel to the port city, taxes, and fees as all part of the cost.

You can of course save on airfare if you are close to a port city, fir example you can sail out of New York if you live in that area year round, but in February the first and last day of the voyage won't be exactly sit on the deck and get a tan weather. Flying to Lauderdale and Miami can be very inexpensive, but if you hit one of the school vacation weeks, the airfares may already be gone, so don't wait once you make up your mind.