There were some surprises about visiting the Hoover Dam, based on the assumptions I made from watching the movie Fools Rush In.
1) The Hoover Dam is gated and patrolled. You don't just drive right up to it and hop out.
2) Consequently, the Dam has a closing time. Don't expect to drive right across it during the nighttime hours. I believe it closes somewhere around 8:00 or 9:00 PM
3) It is recommended that you DO NOT sit on the ledge around the dam.
4) You actually DO toss a coin in if you want to. We saw the evidence and added our wishes to the mix.
5) Remember to Enjoy the sight of fresh water... It's the last of it for a long time if you're heading west through the desert!