This is the question I dread, the capstone of the interview, where I am to show (I guess) my interest and enthusiasm for the job/students/school/department, but NOT ask any questions that I could have looked up myself by perusing the department's website.
I always default to some variation on: Tell me about your students. And everybody always says the same thing about their students. And frankly, I have found students to be more or less the same at every school where I've taught. They're diverse. They range in ability. Blah blah blah. I mean, I've never taught anywhere that the undergrads as a whole were just radically better, or worse, or different, than anywhere else.
That stupid question does not seem to have hurt me, so I'm kind of inclined to think that it's just a rote question everyone asks to finish up the interview, but the answer doesn't matter (unless you massively blow it somehow).
So, open discussion here, as first-rounds approacheth: what questions do you have for them?