there are many interesting routes you could take, ive done this and similar in the area many times, theres plenty of options
this is just a broad outline using m/ways too, but you could add off m/way detail, it takes you past the Rhine Falls at Schaffhausen, through the Vosges in France, and back into Germany through the Eifel and Mosel region, Saverne, Trier and Cochem are fine to visit
you could do this in 2 easyish days, but if you have 5 days you can flesh it out a lot
https://goo.gl/maps/J3g18MrFLiazJkkq8