"The Ralph" is the "Ralph Englestad Arena", or UND's hockey arena. Quite a building, it was built in 2000/01 and is a 100 million dollar plus facility.

Don't know about "incentive rides"- At least when I was a student, there was pretty much only one opportunity for non-aviation folks to fly on university aircraft, and that was Parents Weekend. The reason is for liability purposes. You might be able to talk them into a few minutes in a simulator though.

I concur that one day to see the campus is fine, but you might want to spend an extra night and look around the city to decide if Grand Forks is right for you... I enjoyed it, but was ready to head back east after 4 years living there. I do enjoy going back and visiting from time to time though.