That I definitely old enough! Our school takes 8th grade kids to an amusement park for their field trip, and the kids go off in groups or pairs. My boys are 12 and 13, and I was disappointed when Disney made the rule that they have to be 14 to enter the park without an adult. I would have no problem with my boys going into a park without us. Sometimes they want to sleep at the hotel, and I want to get to rope drop. Now I will have to walk back to the gate to get them in.
We actually do spend most of our time together on a family vacation, but sometimes it's nice to have the option of splitting up if we don't all want to do the same things.