Great River Road from Alton to Grafton, and on up to Pere Marquette State Park. Continuing north past I-72 to Jacksonville. Then south along Rt.267 south to Godfrey. And then home. The whole loop was just over 200 miles.
This image is just a bit north of Pere Marquette, and just a bit off Rt. 100. Larger version and "exact"location at Panoramio.