This was a fantastic experience.
The tour took us over the Hoover Dam, Lake Mead and into the Grand Canyon. The views are amazing. At the landing site inside the canyon they serve you champagne and some food. There were four other passengers, for a total of six. We rotated seats on the way back, everyone got to experience different views.
Our pilot seemed like a consummate professional and we always felt perfectly safe. (Although there was some choppy air, which it turns out is a little more nerve-wracking in a helicopter than aboard a jetliner.) Our pilot was also a font of knowledge about the sights we were passing and the surrounding countryside.