Princess is a great fit for us. We love their mini-suites because we spend a lot of our time there (more than most cruiser's

), on the balcony, napping, watching movies, reading. And we like the ship's that have small decks on the stern (Island Princess for example). We don't mind seeing where we've been! The dining room food is good and the Horizon court is much more "navigable" than Carnival's buffet, where you can walk yourself to death just finding a desert

!
The crew on both Princess and Carnival are great! Sometimes I wonder how they keep up the "cheerfullness"

!
Carnival is our second choice, mainly because of price and that they sail out of Galveston. Galveston (Houston) is easy for us to fly or drive to. I probably would recommend Carnival to a new cruiser of our age, but I'd recommend a 7 day cruise. Despite what they've tried to do, the shorter cruise's still attract the "party" people. If a 21 year old asked me, I'd recommend one of the shorter cruise's.
It really depends on the person(s) asking. I have a friend who wouldn't be happy with less than Crystal or Cunard and another friend who'd be happy with Carnival or NCL.
I think it's great that this site helps new cruiser's make a good decision.