You are wrong Josep, its obvious you never have travelled outside the motorway, and are refusing the comfy of a modern SatNav... Maps!? Green lines!? What !?
Northern Germany is scenic with forrests, old towns and scenic villages.
Schleswig-Holstein is in the far North, with Mecklenburg Vorpommern more East (excuses for misstypo's). The costal line has huge crete cliffs like the UK, with country roads twisting and curving through the landscape. Ideal when arriving through Puttgarden.
Just follow f.e the Weser, Elbe or Ems river up South. I would recommend both the Elbe and the Weser river, the Weser route is perhaps more towards Winterberg direction.
In Lauenförde, Weserbergland, You wil find an excellent and affordable motorcycle hotel, Villa Löwenherz. If You Travel more east via the city of Osnabrück, Youf will find the excellent bike motel 'Altes Farmhaus' in the small village of Lienen. Excellent kitchen too!
I assume You use a SatNav like most do. Just put it on 'choose twisty route' (thats an valuable option on any recent TomTom Rider, I can't judge for Garmin but I sure that they copied it too
). You will be surpriced!