A bit more Cincy info...
Along with the Little Miami Scenic Trail (it's paved, not a dirt or gravel trail and follows the Little Miami River.) there are also countless great scenic cycling routes in N. Ky and in OH that follow the Ohio River. It's riding on the roads, but they are very common cycling routes that aren't heavily traveled and motorists are typically aware of cyclists. My favorite of which takes you up and down some serious hills (The Twin Sisters), then passes by the
Rabbit Hash General Store before following the river for a bit then back up some hills and past
Big Bone Lick State Park (I couldn't have made that name up if I tried.) Large salt lick in the area that attracted large prehistoric animals like mammoths and such which in turn got stuck in the boggy swamps and died. No disc golf course there, but an interesting place none the less. If I remember correctly it's about a 30+ mile loop but feels a lot longer because of the hills.
Thanks to the politicking of one of the local bike shops, many of the Cincy streets have added bike lanes in the past year.
The Little Miami Scenic Trail is fairly close to the brand spanking new Cincy course up in Goshen.
Osage Grove DGC Enjoyable course that's only gonna get better as it "beats in".
Miami Whitewater Forest has an OLD (like Mach I old, fairly short lengths, etc.) 9 hole course and about 10 miles of paved trails. Huge park are pretty nice overall. This place is packed come summer time.
Currently in the works is another paved trail system that is planned to completely circle CVG airport with short spur trails that connect the planned 23 mile loop (currently only 2-3 miles complete) to some of the larger surrounding neighborhoods. Something to think about for the future.