I think it is essential to know who the PD is and the mission of the department. If you don't meet with him/her, I would say high or take a couple minutes at the end of the day if you're serious about a place.
With that said, I do interviews and a few people don't interview with the PD. It's actually random. If ten people interview they won't all get to interview with the PD. You should at the very least be meeting with an associate/assistant PD though, they usually have the same pull when it comes to rank list...