Although I won't be solo with a teenager, I recently did such a trip. I remember doing one thing that he really appreciated. He'd agreed to meet me at CRT for lunch, but morning was "on your own". He slept in, but of course, I was in MK all morning. Just before lunch, I picked up a FP at his favorite ride, SM, to surprise him at lunch. Then after lunch off he went, with a big smile on his face, knowing he wouldn't have to wait.