Read some Yelp reviews about there being free parking further away from the visitors center... Yes, but it's pretty far so you might want to reconsider it especially if you have small kids and it's over 100 degrees out.
The views are pretty cool, tons of tourists so be careful when driving through. If you plan on taking a tour, park at the visitor center. It'll be the first parking structure (with signs) on your left. Parking is $10. Tours to the power plant were still available and was $15, the other tour was sold out. I didn't think the power plant tour was worth it. First you watch a brief video about the history then you go down an elevator to see pipes and learn more history then you go up the elevator to see the power plant and learn more history. After that you walk through a mini museum and learn more history and then you can head outside and take a ton of pretty pictures of the dam and bridge. I wasn't able to do the other tour, but I think I would like to.
I wish I had more time to explore the area and walk around a bit more outside of the tour area though. I heard the higher up you go, the better the views will be! Oh well, next time!