Excellent day trip. The helicopter pilot was brilliant and very informative taking us over Hoover dam and the Grand Canyon. The float boat ride was also excellent. Brian the boat driver was very funny and had us all in stitches. If you are going to do this I would recommend you pack a raincoat. They gave us plastic ponchos but everyone's ripped in the wind so we still got wet, but it was loads of fun.
The Grand Canyon part was a disappointment, they didn't clearly explain how it would work, you only fly over you don't get to see from foot and you then spend 10 minutes in the shop but everyone left their bags in the helicopter because we didn't know what was happening.
Colorado River was brilliant, highly recommend. Tour guide very good, scenes breath-taking
Do this trip! See the Dam from the base, in a restricted area. Amazing views and great knowledge from the tour guide. Only add on needed is maybe the sky walk to see the Grand Canyon from the edge rather than the helicopter.