My kid hasn't yet, but certainly plans to. Her camp has a great program for CILTs (they call them Campers in Leadership Training, not Counselors in Training there.)
One reason she is on this path is b/c
I did it as a teen and it was great! It really is a training program, so CITs get a lot of the joy of being a camper, still, along with guidance in becoming a leader who helps create the joy for others. The leadership training I got from my CIT and counselor experiences enriched all the jobs I've held in my adult life, and it looks great on a college application.
If what your DS has liked about camp has included the "group enthusiasm" stuff, and he can stand younger kids, then he is perfectly suited for being a CIT next year. On the other hand, some kids love camp for the individual opportunities for personal growth in a specific skill or area, such as a sport or music concentration, and the group stuff is just kind of gravy. If he falls into that category, he may be better off looking for some kind of internship program or just a camp environment geared toward older kids.
That's my 2 cents anyway, but of course you know your guy best.

to him, though, because it is hard to say goodby to those carefree camper days!