Seeing as how I am there every other weekend, I can give a fairly good ranking of where to play in Pittsburgh on a regular basis:
1. Stopping in to see Chris at Bradish Street Pinball Parlor would be first on the list. As alichino said, the games are flawlessly maintained, Chris is great to hang out with and talk pinball and the whole experience is overall just great.
2. Kickback would be my second choice. It's almost a little too "trendy" for a guy like me, but the people are great and there are some nice machines there. Worth it just to go in, go up and play Monaco.
3. Pinball Perfection would be my third stop...but only if it is above 60 degrees outside. Over 200 machines with about half of them working on a rotating basis. TONS of obscure titles that you are not going to see anywhere else 'locally in the field'". Granted, not every one works, but it's still worth it to bang out games on the likes of Butterfly, Faces, Car Hop, Beat Time, Centigrade 37, Star Race and all of the other exotic titles that are in there. Friday nights and Saturday afternoons are your only options here.
4. Ace's Breakaway downtown. WOZ, Avengers, Metallica, X-Men, Sopranos, Family Guy, Attack From Mars and an eighth I can't remember off the top of my head.
5. After that, you get into the local establishments that have a machine or two (Doublewide Grill, Rowdy Bucks and others). Of these, my favorite is Hambone's (right down the street from Kickback), mainly because you get WOZ, STTNG and POTC.
And since I live in Fairmont, you can play unlimited on my three machines on the way up or back after you pick me up! Enjoy you visit to the 'burgh!!!