I guess I'm old-fashioned. We are going on our first cruise with our 13 and 14 year old this summer, and the rule will be that they can do what they want to do during the day, but they must report for dinner, unless they've cleared other plans with us. Then they can do what they would like until about 11; staying out all night would *not* be an option! We have already bought walkie-talkies for them, and will check in with them periodically. We have two family excursions planned. They may choose to do other things (such as a teen excursion) at the other two ports, but they will not be allowed to stay on the ship while we are at port.
Oh, and the first time they are found to be doing something inappropriate (and that includes silly stunts like riding up and down in the elevators, which causes delays for the other passengers) they will lose a lot of their privileges.
This is my first cruise, so I don't know what to expect, but it **really** bugs me when I see parents who don't take responsibility for supervising their kids. I see this at the malls often... kids who are left their by their parents who are running around, rough-housing and being, at best disruptive and, at worst, colliding with other patrons. I don't see "But, it is his/her/our vacation" as being an excuse for not supervising the teens. It is also everyone else's vacation, and, these are not their kids and their responsibility... but mine.