Totally recommend you see the Hoover Dam at least once. Very impressive. We went on the Friday after Thanksgiving. Unfortunately, this was also the BUSIEST day to visit, as we were told by the guides. We drove down from Las Vegas and parked in parking lot (fee) and then walked over to get our tickets which we prepaid online. The whole tour is about 30-45 minutes long with a short movie explaining the history of the dam then onto a walking tour with a guide down below in the dam. Then you can do your own walking on the road above the dam. The traffic on the road above the dam was pretty crowded.