I enjoyed my interview time at Harvard. They let me stay 3 nights at Vanderbilt Hall (the dorm) with one of the dental students. You really get a great feel for the school atmosphere that way and I would recommend that you do that if you can. I interviewed almost two years ago there, so my memory is hazy, but I remember the interview being not stressful at all. One of my interviews was with a faculty member and one is with a 4th year.
It was also nice because I interviewed at BU and Tufts the next days as well with out having to pay for a hotel 👍