Highland Scenic Highway (West Virginia S.R. 150), 44.93 miles out and back. 4490 feet of climbing. Wide, parkway road, not a single stop sign or traffic light, at least 3 restrooms and scenic lookouts each way. One good 1500 foot climb each way as well. The turnaround point is a visitor's center at S.R. 150 and S.R. 55 with restrooms and a water fountain. You'll MAYBE see 15 cars the entire 45 miles.
The other neat thing about this road is that they close it to vehicles during the winter but keep it open to cross country skiers and hikers.
Start at the parking lot at U.S. 219 and W.V. S.R. 150, a few miles north of Marlinton, WV. If you're in the area, stop by by the Dirtbean bike shop, inn, and training center.
I don't have any photos of the route itself, but you can find some here and here and here.
I do have a photo of this thing, however, which we found a few years ago along the off-road hiking/biking trail less than a mile from the parking lot where you begin the ride:
This picture describes how I felt after completing this ride the last time I did it while chasing Pete S. the whole time, who, according to him "was feeling good" that day.