Jaime O,
Unfortunately we couldn't connect in Pittsburgh last year. I don't go there like I use to. I'll leave you with my two favorite places:
North Boundary Park just north of Cranberry. Follow the electrical wires up hill. There you'll discover a wonderful Black Oak to climb at the top of the hill. Though it's nestled on the edge of the woods, you can't miss it -really.
The other is located in Oakmont. There's a natue reserve at the top of hill called Dark(or Shady) Hollow. Follow the trails and discover trees. This backs up to Penn Hills. There's a creek that separates them.
I also traveled up to McConnells Mills State Park. With the leaves changing this would be the time to see some beautiful sceneray around the covered bridge and old mill on Slippery Rock Creek. This area is open to rock climbers. Though I've climbed a tree or two there, I found it to be amazingly void of good trees. I'm sure one of the rugged trails leads to a good tree. I just never found one.