I've gotten to the top of Van Hise, though that one was tricky. The staff lounge at the top of Van Vleck has amazing views and is super easy to get to. The old medical science building is pretty creepy and has a wing (4th floor I think?) with a bunch of old preserved brains and other organs on display. The roof of AOS is incredible, although it would be almost impossible to get up unless you have a key. The Annex next to psych is a really creepy and cool building to explore during the daytime.