Royal Caribbean all the way! I really enjoyed both my cruises with them. If one has the money the Crown Loft Suites on the (Oasis and Allure) ships are incredible. It was like having our own two story/two bathroom apartment at sea complete with a door bell. I imagine the rest of the state rooms must be nice as well.
These two ships are like being on a floating city. There is a wide variety of activities from Broadway style plays, live music, zip lining, wall climbing, an old time boardwalk complete with a Merry-go-round, a basketball court, gym, swimming pools, nightclubs/lounges, dancing, Central Park, various restaurants, a comedy club, casino, food and more food, bars...etc.
The only thing that could potentially impact your trip is if you have bad weather during your week. It's pays to do some research for the time of year you plan to cruise.