I went to Hoover Dam yesterday on a Tuesday afternoon and found this landmark to be a nice place to visit on a beautiful blue sky day, but was exhausted within a few minutes of arriving because of the hordes of people. To enjoy something outdoors with SO many people was too difficult and I was glad that I didn't pay the $11 fee to see the visitor center and take the tour.
I think it's a MUCH better use of time to park for FREE near the memorial bridge and enter for FREE to this bridge to view a beautiful overlook of the dam. I paid $7 to park near the visitor center with all the throngs of people, so do yourself a favor and save money and time by visiting the bridge, which had interesting displays on how the bridge was constructed and you can view it all for FREE.
As an avid outdoors person, If it weren't a beautiful day outside, I wouldn't go out of my way to visit this overly crowded place that is mainly a lot of concrete.