White_birch, your route through SW Ohio is okay, but I've got a more interesting route: ridewithgps.com/routes/11790518, with Points of Interest added to the route map.

This local map starts at your Mile 776.

At your Mile 780, stay on the trail.

On my map:
Follow the bike trail almost to it's end near Mariemont OH at mile 12.7. Route 50 is a main highway, but not too busy outside of rush hour, and they are used to seeing bikes there.

Mile 14.2 The local Graeter's Ice Cream has a shop in the center of Mariemont--get the chip flavors!
Mile 16.9 turn in to Armleder Park, then take the connector to the Lunken Airport trail. You might see business jets taking off.
Mile 22.2 Lunken Terminal building is a small 1930s Art Deco lobby, with a 1930s tiny airplane hanging from the ceiling, and murals. Also a restaurant (with outdoor seating in the back, and you can leave a bike in sight there.)
Then take Airport Road to connect to Riverside Drive along the Ohio River. It's a reserved bike lane to downtown.
Mile 24.3 St Rose Church has great views of the river from it's back parking lot.
Mile 26 The river side parks begin. Either stay on the road or take the park paths if you aren't in a hurry.
Mile 28 the new Smale Park has views of downtown, the river, the 1865 Suspension Bridge, and has many interesting features to explore. There's a bike station that has locking bike storage inside.
Mile 29 head back a mile to cross on the 1890s Purple Bridge, now it's for pedestrians and bikes only.
Follow KY Route 8 to the Anderson Ferry. Bikes are $1.00, and it's an interesting trip across the river.

Some of the roads on the way to Indiana are main highways, but avoid rush hour and you'll be fine. There's no good alternative routes without adding quite a few miles to the north. For example, this route--which only avoids maybe 5 miles of busy highway. But it's a scenic route through the Whitewater River valley, on mostly lightly traveled roads.

EDIT -- added links