We cruised on the Jewel from Miami returning on Christmas day with a group of 12 including 5 under the age of 18. Was one of the best vacations we've had ever! The kids did not participate in the kids programs, but had some fun anyway. St. Thomas was the best snorkeling ever, Coki Beach is GREAT! Lots of fish, be sure to get dog biscuits and feed them when you are there.
The kids loved the ice cream machines... lots and lots of cones last week! I was a bit disappointed in the food as we have sailed Princess before and I must say, the Princess line has spoiled us. If you plan on eating in any of the 'speciality' eateries, be sure to make reservations as soon as you get on board.
Salt water pools kinda suck, as the kids are not used to salt water in the eyes, be sure to bring goggles. Last time we cruised with Princess it was fresh water and we love that feature.