Usually there's a blanket weekend awarded to 2/C, so unless your mid is weekend ineligible for some reason, he'll be free from Friday through Sunday aside from the game. I think there's a brief and other funtivities for parents on Thursday, not sure what else.
The biggest thing about parent's weekend is that on Friday you can go to classes with your mid, eat in King Hall, and go up to their room in Bancroft (which probably will look a little different than it did during Plebe Parents' Weekend). Use common sense about which classes you go to (your mid will help you think this through). For example, if he has a history class with zero empty seats or something wicked boring like EE, maybe don't go to those classes.
A quick word of caution: be mindful, and please don't take this the wrong way, that your mid's got a lot of stuff going on. It may have just been the timing because my class's parents' weekend was at a weird time, but 2/C parents' weekend was very stressful for me as far as balancing school (it was a really busy week) and making sure my parents were doing alright.