If you can, go to the Thursday night activities. Those will give you a chance to unwind and meet students and other interviewees, and there's nothing better than a few familiar faces when you arrive Friday morning. And on Friday, have fun. Seriously. UMich won me over with their interview day. It's a full but low-stress day, and the faculty, staff, and students are kind and personable. Interviews and MMIs are before lunch, which I like because you get it out of the way before the Untour. Of the five interviews I've been on so far, this was by far my favorite one. If you have any more specific questions, feel free to ask. Best of luck!