Along the Rhine river in Western Germany there’s a lot of scenic places to go. The more south you go along the Rhine, the nicer it gets.
One area you should not miss is Boppard, a place which is famous for it’s scenic free meander and for its local White Wine. Like most villages in the surrounding, it is easy to walk around and to enjoy the scenenery of historical housing and to relax from the noisy, grey cities. You could take a seat anywhere and order a glass of Boppard’s white wine. 
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From Dusseldorf, it would take you a bit more than one hour to drive. The scenery is fantastic, especially when you cross the Ahrtal autobahn bridge near Ahrweiler.
We did not take a boat trip but if you bring time, it’s worth a cruise! 