Wow! On my way to Mount Washington I unexpectedly noticed Grandview Park and decided to stop. I'm glad I did! It provides some of the best views of Pittsburgh's skyline.
It's not entirely easy to spot -- it's set in a neighborhood, really. Just park on the street somewhere.
Also, I noticed there were some hiking trails down the hill. I don't know how far they lead, as I had to get going. Otherwise, the park is not entirely big. I think I spent an hour there. Just something to note.