Took my in-laws on the South Rim Bus Tour, and overall it was a good experience.
The shuttle came promptly to our hotel at 6:20 am and took us to the check-in center at the PH Miracle Mile Shops. Check-in took a while (long line) and the breakfast snack was a little weak (pre-packaged sticky bun and small cup of coffee).
Our driver was Coach Ed who was a little quirky but a real friendly guy. He was very informative and had a lot of useful commentary. The video sound system on the bus was all wacky though - some movies had softer volume and others were so very loud no one could sleep. I appreciated his efforts to beat the other buses so we could always get first crack at the rest areas, food, bathrooms, stops, etc. Our tour was supposed to arrive back in Vegas by 9:30 but we were dropped off in front of our hotel by 8:45 which we truly appreciated.
The rest stop in Kingman was a little run down but got the job done. Lunch was a buffet in Williams and actually not that bad. When we finally got to the South Rim, we had 1 hour at one viewpoint and 1 hour at another. That was definitely enough time to snap dozens of photos, hit the bathrooms, and grab a snack.
On the way back, we saw the Hoover Dam at night.
I would recommend this tour.