my DD (25) and I just came back from a 7 night western... The only time we saw a lot of kids was when we were near the Mickey Pool. We'd go up to deck 10 to the over 18 section forward, so you'll only see children walking through to the basketball courts, not sitting there, screaming, being loud or obnoxious. I didn't really see any "out of control" children either during the whole cruise!!
There's tons for adults to do onboard!! We used the stairs a lot and seemed like the only children using the stairs where the ones running to beat their friends on the elevator.
there were only a few teenagers at the late movies most of the time, but so many empty seats they didn't effect anyone.
And at dinner, we were seated with a group of 3 women, a family of 3 with a 17 year old, and another couple. Daniel didn't feel out of place with a bunch of "older people". He actually looked forward to dining with us all. We had all sorts of games, card tricks and jokes each night to make thing lively.