We have been on lots of these roads. Hwy 50, "the loneliest road in America" that goes from Ocean City, Maryland to West Sacramento, California. Another great road is Hwy 12, a 219 mile river-side trip from Lewiston, Idaho to Missoula, Montana. You can parallel another river from Paradise, California to Bordertown, Nevada on Hwy 70. There are so many, you just need to get out there and find them.
To us, there is a best road less traveled.