The most boring road
We've done some considerable driving this year - to Southern California, Wisconsin and Western Oregon. We've driven across the full width of the following states: Wyoming, Nebraska, Missouri, Minnesota (via I-90), South Dakota, Oregon & Nevada. By far, the drive along I-80 across Nevada is the worst.
It didn't help that there were multiple fires in the area, leaving the sky a dull brown and reducing any mountains in the area to ghostly outlines. Rivers or creeks along the way were dry, the scrub brush was either a dull gray or burned from previous fires. The whole 410 miles was other-worldly, and not in the cool-it's-an-alien-world way, but more like a this-is-where-aliens-send-exiles kind of vibe.
We passed the time by watching an empty soda can vibrate around in the cup holder. I even took video of it.