We have done Princess twice, Celebrity twice, and Carnival once to Mexico but not NCL. If you want a more elegant cruise with great shows go with Princess. True, Carnival is more of a party cruise but it all depends on what you want. When any cruise is over 7 days you tend to get an older crowd.
Any way you cut it, a week or more relaxing on a ship ore a beach beats sitting at home with winter staring us in the face. We are off to Mexico on the Mercury on Oct. 30th. Can't wait.