A general comment.

<< A bit out of the way is Rothenburg ober der Tauber. It's a old walled city & worth a visit. >>

Every German you might personally know and then ask about Rothenburg ob der Tauber will tell you NOT to go there - it was once a wonderful old town. But now it's a hot spot mainly for Japanese tourist groups.

Instead of this (sad to say!) tourist trap I'd suggest Noerdlingen which might well be near a possible way between Bavaria and Frankfurt - and tends to be much more authentic.

Baerbel.