THis was totally worth the small drive from Las Vegas. I would recommend getting there early, the lines to go through the check point entrance can be a bit lengthy and the sun is brutal, if you are in a convertable.
We did the full tour of the powerplant and the Dam. I was rather informed and impressed with the presentation, the staff was comical and interesting. All in all it was worth it. The views are absolutely breath taking and the photo opportunities are amazing.