Route driving Rothenburg to Bacharach !

Here's a suggestion. Any number to towns listed would be worth a stop, although you won't have time for them all. Take A7 to A6 towards Heilbron. Consider a stop-off in Schwäbisch Hall. Near Heilbron, exit the autobahn and drive along the Neckar river. Take a look at Bad Wimpfen. Follow the course of the Neckar river towards Heidelberg. Either continue towards Heidelberg, or head north on B45 at Eberbach to Erbach and Michelstadt. From Michelstadt, head west to Bensheim via Lindenfels. At Bensheim, head north on either A5 or B3 to Darmstadt. After driving through Darmstadt, takke A67 to A3 to A66 via Wiesbaden. A66 becomes B42, continue to Rüdesheim. Take one of the ferries over the Rhine to Bacharach.

Okay ! The map just looks so congested - through Frankfurt or Mannheim !