I'm from the UK, have done some road trips before around the 'area' but this time its a bit longer, have 2 weeks starting from Vegas (few nights there first) to GC to Bryce to Moab to Tetons to Yellowstone and back to SLC for a flight.

There's no difference for me booking off airport it seems, maybe a couple of dollars max but they dont like one way rentals hence renting from LAS.

I can change the car to a 'sedan' of some sort with no concerns about roads etc then by the looks of it, would prefer one over an SUV.

I have a backup reservation with Hertz as heard some locations sell out/have poor selection, am a member of boths rental programmes.