It really depends on the situation. For both POs and position players I would really want to take a class or two and live on campus with some other incoming freshman. Whether that is a short 4 week class or the entire summer doesn't really matter. Get used to having options as far as going to class and doing your homework vs hanging out, partying, girls, sun, etc. It also helps get in a routine. Eat, class, lift, eat, hang out, practice, homework/social activity, etc.
And if I were a position player I would want to play in a local collegiate league. I've found that the transition for pitchers is easier than it is for hitters. So in an ideal world I'd live on campus from June to end of July, play in a league and come home for a few weeks in August for time with family/friends before school starts back up at the end of August.
For some there aren't options. In our case he came home from prom weekend on a Sunday and had class Tuesday morning. It was worth it for the lifting alone, it really didn't compare to anything he would've been doing on his own at the gym.