the case may be, for a large group is the lack of a place to all meet and just hang out. We did a few family reunions of 20+ people on cruises. There are public areas that are sort of like a living room, but there isn't any sort of living room per se. The cabins are too small to congregate, so dinner ends up being the only time you're really all together. Since there are early and late seatings for dinner, the staff would like you to hurry up and eat so they can prep for the next seating. You can't just hang around the table and visit.

On the other hand, it was nice to be able to disappear into your own cubby-hole when the need arose.

One thing to think about is whether or not your kid is a "joiner" or not. Some in our group took right to the kid's club activities while others would prefer not to be stuck in a group and would just wander. Be wary of the teen club, these are not (in my experience) filled with teens that would likely share your values. The allure of "I'm stuck on this boat and I'll never see this chick/dude again" can be dangerous.