Just got back from Pittsburgh to interview at Tepper. I had applied during the interview request phase so this was in the works before I submitted my application.
I think they value the onsite interview more than some schools so if you have the means or time to make the trip I would recommend it. I think everyone gets to interview with someone from admissions(no second years or the like).
The questions were pretty standard:
1. Talk about your past career and education
2. Why an MBA? Why Tepper?
3. Why an MBA now?
4. Talk about your leadership style.
5. How would people you have worked with describe your contribution to a team?
There may have been more but I can't remember them off the top of my head.
The lunch with a first year and class visit were both valuable and the tour is good if you've never seen the campus(although they skip over a lot of it). All in all it was worth the trip if you're seriously considering it.