The round trip time was 2.0 hours. It could be done much faster as the straight line distance is only around 75 nm. But, this was a sightseeing tour, so I followed the river once I got out of the Class B around McCarran. I also flew at 55% power so I could see everything.
As for the altitude, I flew at 9,500 feet based on the recommendation of the check ride instructor from WestAir Aviation. There are many sightseeing aircraft flying lower. Lots of helicopters and twin engine tour planes. Most of the tour planes are flown by low time commercial pilots - translation: 20 somethings who take too many chances. To provide a margin of safety, I flew well above them until I had to land at the Grand Canyon West airport.
When I departed, I flew west over the canyon on climbout up to 8,500 feet and got an excellent view of the features.
If you are going to rent a plane, plan on about 2 hours for a check out beforehand. I've done checkouts in .6 hours and this one took about 1.0 hours, but there is paperwork and preflight work that must be done.