My partner and I will be in las Vegas on the 19th of September, we would like to see hoover dam, some of route 66, grand canyon south rim, Zion n.p and Bryce canyon n.p. firstly is there any car hire companies in las Vegas that don't charge a fee for under 25 year olds as I'm 22?? We would like to start the trip on the 21st of September and be back in Vegas by the 24th is this enough time?? Any advice or suggestions would be amazing!!