I have to agree with Barb on this one.
We go as a family, we have a ds-15 (almost) and he loves the cruise. However that being said, during the day (and most of the night

) he is out with friends.
Dh and I had an awesome time in the adult areas. Now I never made it to the gym, too tired from eating, but if they made the gym available to the younger set, I would imagine there would be all kinds of problems:
-kids who never worked out, all of a sudden need to go in and do not know what they are doing. Children (and even some adults) could get hurt. Ds did some weighlifting in an afterschool program and they were taught the proper way to lift and it was weeks before they were allowed to go on their own.
-kids using the equipment to play like Barb mentioned. Have you never seen AFHV, the kid playing on the treadmill and bam! the kid falls on his face.
-just the fact that kids using this area, the equipment will not be available to adults as easy. I know in walking in a gym, if there is not anything available, I go home. This kills one of the adult
Perhaps
DCL could come up with a time or two when an adult would accompany someone 16 or 17. But I would make it very limited. And 8:30 is not the time. We had the same problem with our son and late seating.
JMHO