Yes there are some lovely back roads in the East, South, and Midwest - -
And far fewer paved back roads in the West.
But the West has an abundance of public lands - -
Glorious natural landscapes that are rare east of the Rockies.
East or West, if you are willing to do a little dirt, the payoffs are big.
This is especially true if there is only a short dirt section in a route.
For example, the main highway is 30 miles with shoulders and moderate traffic.
The old road is 32 miles with a 6-mile dirt section and almost zero traffic.
For me, the choice is obvious.
Also, you have to be willing to ride extra miles in the West to discover the empty paved roads.
If you want the direct routes - it will usually have traffic, although often not that much.
But if you are willing to zig and zag some, you find the jewels.
For example, US 50 across Nevada - supposedly the "Loneliest Road" - ain't that lonely.
But US 6 to the south has half the traffic - profoundly empty.
Similarly, in Wyoming's Grand Teton N.P. back road options are there.
After riding the park loop, you can swing around Mormon Row, then use Spring Gulch Road into Jackson.