California - 29 from Calistoga to Middletown, 50 from Placerville to Tahoe, 1 from SF to Bodega Bay (and all the hidden roads back to 101). All to be driven in the ''off'' hours to get any fun out of them. Another favorite, 9 in the Colorado Rockies spectac..
Oh, let's throw in "The-Road-To-The-Sun" in Glacier National Park, probably the best road EVER built by man. Of course part of what makes it so great is it possesses some of the most impressive scenery ever created, so it's a little hard to watch the road. On the down side I don't know if it ever has been completely empty of buses or motorhomes