There is a beautiful hiking trail along the Rhine, called Rheinsteig, that runs 320 km from Wiesbaden to Bonn (or the other way round). I only hiked the first 80 km, walking through vineyards and villages, and getting no sketching done except these two- Schloß Vollrads in Johannisberg and a glimpse of half timbered houses in Rüdesheim.