This was on my to-do list when coming to Vegas along with the Grand Canyon of course. To be honest it's cool to go see it and learn some facts but my wife and I paid $60 for the "full package" and that got us a 20 year old 10 minute video, a walk around for about 1 1/2 looking at the same few items in the small exhibit they have so there wasn't much to look at while we waited.
We then went down into the dam to view some power plant rooms and eventually got to go down further and into some small tunnels to view the air vent in the actual wall of the dam which was cool.
One big problem with all this is several times they pack you into an elevator and I do mean PACK you. I'm talking butt crack to crotch here people... My wife wasn't happy about this and it stressed her out every time we had to get back on. I know you have to save time and a little money but 20+ people even on a large elevator is overkill. For sure change this.
It's a catch 22 because it's cool getting to go down into the dam but dropping $60 is pretty expensive for a government run facility. God forbid you have to pay for 2-3 more kids in addition. At that point, you would have to take out a second mortgage.