Shop around the Strip to find the best deal for a bus trip to see the Hoover Dam. Once you found one, sit back and relax. The one I found picked me up right at my hotel and then proceeded to pick up others. From there, they met up with other buses to then transfer passengers to their tour destinations. Depending upon your tour, you get a tour of Boulder, Nevada, where the workers on the Dam stayed, as well as how the town was created.
When you finally get to the Hoover Dam, you don't necessarily have to take the tour. I feel a little claustrophobic by the thought of pipes and water surrounding me. I walked along the walkway from one side of the Dam to the other. On your way, stop on the state border between Nevada and Arizona to take a picture of you in two locations. When you get to the opposite side, walk up the stairs to get a higher view of the back side of the dam.
Although I don't remember how much my tour was, I do remember it was on the lower end of the Strip near the MGM and on the same side of the Walgreens/CVS. It was on the side of a few shops. Hopefully this is enough to give you a rough idea where I found my tour.