We had the Duquesne Incline pegged as one of our must do's but after all things considered, it was just an average experience.
The trip to Duquesne Incline was very confusing, at best. From Carson road, its actually quite easy to miss the turn off point. The lower station is a red building surrounded by a graveled lot which CANNOT BE PARKED IN. Consider this a warning. What you actually have to do is keep an eye for a turnoff at station square which will lead you to a paid parking lot.
OR.
You can drive to the top on Grandview street and score some choice street parking. Use Altius restaurant as a landmark to guide you up there.
BE AWARE...
If you choose to ride from the top down, you can't pay until you reach the bottom which adds more confusion. The staff looks to collect a voucher when you get off from the bottom, but if you didn't pay...then you'll obviously have no voucher. The voucherless then have to get in line and work with the ticketing agent - the whole process may have some historical charm but is very inefficient. It's cash only. You need exact change. And you literally show the ticket master your said exact payment....drop it into a box outside his booth....and he hands you a paper voucher.
As for the incline ride itself, its okay. It's a short ride and the lower back and front windows have been replaced by screens which really disrupts those skyline pictures.
To essentially do this for free, drive up to the top landing at Grandview Street. Take loads of pics from the observation deck or from the lookout point about a quarter mile down the hill. Then, head into the small museum to read up on all the facts. Sure, you don't get to ride the incline but you're not missing much.