Utah State Route 12 or Scenic Byway 12 starts south of Panguitch at an intersection with US-89, and continues west to east for nearly 200 km. It is also known as "Highway 12 — A Journey Through Time Scenic Byway" (what a mouthfull) and is regarded as one of the most scenic highways in the US. We would certainly vouch for that.
Of course we didn't know any of this when we set out on it and we were gobschmacked. It was fantastic.
The top shot was taken soon after the highway started at the I89 as we passed through Bryce Canyon NP. The bottom shot is just out of Henrieville in the Escalante Grand Staircase NP