first cruise, our daughter was a bit reserved about going and at the time she was about 3 1/2. when we later picked her up that first day, she didn't want to leave. from that point on, we had to make a schedule with her of when she could go. it was a bit traumatic (for us!) - we never left her with anyone up until then.
on the second cruise, we were ready/prepared and let her do as she liked - every day, on average it had to be 4 hours that she spent at the club. I began to wonder - just who's vacation was it, hers or ours?