As a lifelong SW Ohio resident, I have to confess that there are not a lot of unpaved options for traversing the state in any direction. That said, there are plenty of scenic backroads, especially in the East and Southeast . SE of Columbus there's Wayne National Forest, Shawnee State Forest, Tar Hollow State Forest, and others, all of which offer great scenery and are off the beaten path. Shawnee, in particular, has a number of well marked and well maintained unpaved Forestry roads. Check out the Ohio DNR website. Also check out GravelMap.com - it's a gravel road wiki of sorts, with updates once in a while. Once you get farther north, past Wlimington / Washington Courthouse, the terrain flattens and the scenery is primarily crops in the field. If you need to make time, US 35 is four lane over most of it's distance. Safe Travels!