This was an extremely well-organized tour group. The guides (ours was Jeff) were knowledgable and entertaining, and obviously loved their jobs.
This tour operator has permission to set out from a restricted area right below the Hoover Dam and the Mike O'Callaghan–Pat Tillman Memorial Bridge. Jeff gave us a lot of information about both structures before we set off down river. This is a long and relaxing float. There is no paddling, and no white water. You don't have to do anything but gaze at the canyon walls, blue sky, and clear emerald water. If it's hot, you can swim, but the water is a constant 54 degrees. It would probably be very welcome on a blazing hot summer day.
Halfway through the trip, we stopped for a very good lunch of turkey, ham or veggie wraps, chips, apple, cookies and water. We sat on the sand or climbed up the rocks to eat, which was great for us, but other people found uncomfortable. There was a portable "loo", which some people thought to be "icky", but this is a remote area and there are no bathrooms in the canyon. So don't drink a lot of coffee before getting on the bus!
There is a lot of history on this river, and Jeff kept us entertained the whole time. We didn't see any wildlife other than water birds, but there are often bighorn sheep, we were told.
Be sure to use sunscreen and take a jacket/cover-up, as the sun reflecting off the water can give you a nice burn. If you take a hat, make sure you have a strap, as the wind can get pretty brisk in parts of the canyon and your hat may become a kite.
If you have active kids, this isn't a great activity for them as there isn't much to do but relax or sleep. And, not surprisingly, there aren't any cell towers or WiFi.