My wife and I have only traveled on two lines, Cunard and Disney. This means our fellow passengers have ranged from the older and dressier crowd to the younger pirate-clad crowd! We have felt comfortable on both and enjoyed ourselves with few reservations.
We do, however like to up-charge for the extra attention and added privacy. On Cunard we traveled Princess Class and on the Dream we travel in Concierge. We have found Concierge Level on the Dream fits our need for additional quiet spaces.
We do not have children and we still love traveling DCL. What we have found in researching other lines is that we do not need a casino, we like cocktails but not "party drinking," we do not need a disco, zip-line, rock wall, or surf pool. We understand our fares "subsidize" children's spaces we will never use but on Oasis of the Seas, we would be subsidizing all of the above and have no interest.