Like L.T., I also was looking to get away from the La Vegas neon jungle and experience some nature. My son and I got a shuttle ride over to Lake Mead and then hopped on the boat for the cruise.
Coming as we were from an ocean and bay environment, it was fascinating for my boy to experience a lake out in the middle of the desert. We enjoyed seeing Hoover Dam from down below since we had previously driven over the top of it. The Lake Mead tour was especially informative as to the geography, archeology and impact of lowering Lake water levels that threaten the ecology of the region. There were glimpses of birds, fish, and native plants. I like that some history of the area Native Americans were also incorporated into the tour.
Didn't really buy anything or go drinking at the bar. I would recommend this tour highly. In my opinion, there is not much of value to be found in Las Vegas but if you can get out into this beautiful region, there is much enjoyment to be found in the great Nevada outdoors.