Having experimented a bunch watching college hockey, the best seats in any arena are in the corner and on the glass. Up close, unobstructed, and undistorted view of everywhere on the ice.You have to be in the area where the corner of the ice would be if it was a full rectangle for that to work. If you're even a row back or two, the glass will severely distort your view.
Most NHL arenas use the corners for zamboni entrances and whatnot, though. I think PNC only has one corner where you can actually get seats.
Besides that, you don't want to be behind the benches unless you're at least 10 rows up, unless you like watching trainers and whatnot.
But really, any seat in the arena will be great. I've sat in the literal last row of arenas before, and you can still see just about everything. You'll be able to see the faces of players and whatnot much better from the lower bowl, but you can see full ice plays develop better from up high. Forced to choose, I'd say get a lower bowl seat near the corner on the end where your team shoots twice, 10+ rows up. The club sections have their own restrooms and food, but the food and beer selection is better if you go to the main concourse and the restroom lines aren't actually much shorter anyway.