It was 115 yesterday so that did put a damper on our activities! I had purchased the tour tickets ahead of time and inquired about the longer tour (That you can't buy online until you get there) and it was a 2 hour wait before the next one was available. We decided against it. In hindsight, we should have taken it - gone to see the outside of the dam, drove up to see the viewpoints, get an ice cream in the overpriced cafe, and visited the giftshop, taken our time and then take the longer tour. The regular tour takes you to 2 power plant things. It's good - but wish we had changed things around and waited for the big one. I was disappointed in that you're in tunnels and our group wasn't great about huddling together (it's more like 70 degrees inside) so that everyone can hear what the tour guide is saying so we missed a whole section as we were too far away. If that happens to you, just speak up politely and get your family in hearing distance - you'll never see these people again and they're not exactly being considerate to think nothing of people standing in the hallway while they stand in a loose group in front of the tour guide. Learned my lesson today!! Guard at the first driving checkpoint told me that the bighorn sheep are out in the early morning and evening - and hide during the heat... hope you get to see one! Also - park at the bridge overlook to walk up and walk across the bridge - amazing views!!