Just returned from Atlanta. We interviewed about 25 applicants for other position. I was really blown away by the variance in the amount of background research candidates had done on our university/department. Some were able to reference the research areas of the interviewers...others seemed not to know much more than what state we are in.
Obviously the amount of time you have to spend on any given position is a function of the number of interviews you have and your (ex ante) interest in the job. However, it seems to me that too many candidates put little to no effort in preparing to meet with us. A few of our committee members were highly swayed by this fact.
If you happen to get a flyout somewhere, SPEND TIME DOING YOUR HOMEWORK BEFORE YOU GO.