Every time I bring people to Pittsburgh that have never been I must always take them here to the Monongahela incline. This one is convenient because it serves multiple purposes.
There's meter parking in a lot on Shiloh so I can leave the car there, walk across the street if I want a hot dog and/or beer and if kids are along there's Diofore's ice cream which isn't the greatest but hey it's ice cream. At the end of Shiloh there's an observation pad with a great view of the city. From here you can see Heinz field, all of downtown Pittsburgh and directly below is Station Square.
The thing is you can take the incline down to Station Square and while it's not really what it used to be back when I used to go here more often it still has some good places to have a drink or grab a bite. I you go to where the fountains are you can have a good view of the city and Mon river where there are several places with patios and such.
When you're done you get to ride it back up again. I much prefer leaving the car up he hill.
The last time I checked it was 2.50 a trip.