Both Case and UPenn had pretty straight forward interviews. Case will have you interview with two people, usually a faculty member and administrator. Penn only had me interview with one person.The interviews themselves were very laid back. Nothing difficult to answer, or pressing was asked. Don't be surprised if your asked to "tell me a little about yourself." That question came up in both my Case and UPenn interview. Both schools wanted to know why I wanted to go to their school, UPenn especially. My opinion is this, if you show a reasonable amount of interest in their program during the interview, your chances of getting in are great. More so because your interviewing so early with them. Keep in mind that Case likes to emphasize the strength of their clinical program and Penn likes to emphasize their high success rate of getting their students placed into specialty programs. Good luck.
PS. I chose UPenn, maybe I'll see you there.