How about Fallingwater?
The Point. Mt Washington/Grandview Ave overlook. West End Overlook park. Any of the many parks... What are you going for in terms of scenery? Nice view, pretty secluded area, etc?
Got it, less view-y, more seclude-y. I love Hartwood. Let’s see, there’s also the observatory at Riverview Park; North Park has some lovely spots; there’s a covered bridge at McConnell’s Mill park. If you want to drive a ways, the Fallingwater suggestion above is great, and Ohiopyle has some sweet waterfalls, like Cucumber Falls. This is fun!