PIT is my home airport. And you don't need a ticket to get through security. If the planes are landing on Runways 28R, C, L which they usually do you have to get into the US Airways club either in the A concourse or the B concourse. The clubs sit higher than any place else, so you get a great view of the runways pretty much right where the planes touchdown. If you can't get into the clubs then I would suggest going to the ends of the A and B concourse but these spots aren't nearly as good. Good luck!
Depending on the runways being used, i would also suggest the eating area by the McDonalds, they have a good view of on of the runways(sorry not sure which one) but the view is slightly limited off to the sides by concourses A and D.
Why would God make us all so different, if He wanted us to be the same?
I love Pittsburgh Airport. I travel their often. My family lives about 1 hour north of there. I hope you enjoy youself. When you get the pics developed, give me a buzz. I would like to look at them if you don't mind.