We came during the Labor Day weekend and it was very busy, probably because everyone wanted to take pictures of the sunset. The line was out to the street but that did not detour us! It was about a 30 minute wait which wasn't too bad when you are in good company, it goes by quickly. It is $2.50 each way and you can either pay for one way or for roundtrip.
The incline takes you up where you will get a view of Pittsburgh! The skyline was absolutely beautiful at night! There are many great night shots that you can take!
If you ever visit Pittsburgh, you need to do this because it is such a breathtaking sight.