having ridden most of the possible areas mentioned, seems like your time here in the us would be better served just flying into las vegas early (with your own bike or renting), renting a car, and hitting zion national park (about two hours away-one way-by car). the less airport time, the better. zion canyon itself is roughly a 15-mile/24-km, flattish ride from the
main/southern entrance and a must-do. the tourist/hiker shuttles go slowly and won’t pass you unless you pull over and put a foot down.
current entrance fee for an automobile is $35 (good for 7 consecutive days) or if you find a parking spot a mile or two outside the park, cycling in is $20. having cycled zion canyon multiple times, my only regret is that it isn’t closer to me.
https://www.nps.gov/zion/planyourvisit//basicinfo.htm

another alternative for early weekend arrival to las vegas would be to hit death valley national park instead or in addition to zion np. dvnp is roughly the same driving distance away as zion np with some of the most wide-open spaces you’ll ever see in your life. there is also more roadie cycling in dvnp as well. the ride from furnace creek to badwater and back is roughly 35-miles/56-kms. adjacent artist drive is a helluva ascent and descent.
https://www.nps.gov/deva/index.htm


during the week, you could hit the red rock loop, lake mead shoreline and valley of fire state park (or do this last one on the way back from zion np…doing all the paved parts in valley of fire state park would take you 2-3 hrs).

https://www.blm.gov/programs/nationa...ed-rock-canyon

https://www.nps.gov/lake/index.htm

https://parks.nv.gov/parks/valley-of-fire


not to denigrate any of the other areas mentioned but the las vegas area along with the weekend side trip(s) to zion and/or death valley add to the excellent riding while maximizing the riding time.
hope this helps. happy riding and travels!