Good advice, rent a car - the bigger the better! then you have air conditioning, which is seldom found in light aircraft. Most US rentals have automatic speed/throttle control, so you can stretch your legs from time to time.
Do NOT be tempted to rent a convertible. The fabric top is easily cut by robbers, the wind in the hair gets rather dry and dusty going through Death Valley!
The scenery throughout - awesome! much better experiencing driving rather than diving through canyons....