I totally agree with the reply saying once you have it, you will use it to go see a park without having to give it a second thought. Even in the east or south, once you have it you won't have to stop and evaluate whether you should spend money to see this small park or that one, etc.
Of course, if you do NOT plan to travel and be near more than one or two parks, then it would be a waste.
If you are going to have a chance to go out west, just read through Bob's blog posts from the past several weeks and view the places he's shown us. The west has mind-blowing parks that, to me, are the essence of why we travel. You can always wait until you are AT the first park you know you'd like to see and then buy your pass at that time. It will be good for the longest time that way.