At the request of Sean I'm opening up this post for folks to comment on where they sit or where they'd recommend sitting at the Nat.
My personal experience is that there really isn't a bad seat in the house. That's not the homer in me coming out... I've sat just about everywhere except for the section with your own personal tables and you'd be hard fought to find a seat where you don't have a good view of the game action.
There is one section in the upper bowl (can't remember the section) where there is only one way in/out. Also in the "upper" lower bowl there are some seats where you can't see the scoreboard very well.
I spend most of my time either in 108 or 209.
I'm not much of a glass guy as you can't see a lot of the play but with that said, there is something special about being that close to the action once in a while. Of course there is that whole "cost" thing.
For me the perfect seats are about 12 to 15 rows up in the lower bowl corners just above the glass. Close enough to feel the game and get rowdy yet far enough to see the entire ice.
Please share your thoughts in the comments.