4 week driving itinerary in Germany

That sounds similar to my trip this past year (minus the campervan). I spent 30 days traveling around Germany, although I mostly did it by train (with one short 4 day car rental in a small town). I started in Berlin where I spent 4 nights, then made my way south to Nuremberg and stayed there 4 nights (day trips to Bamberg and Regensburg). After that I headed to the Black Forest for 4 nights and stayed in Gengenbach.

Next was the Rhine Valley with 3 nights in Boppard, then Cologne and Aachen, then up to Münsterland. My final stop was Hamburg for several nights then I opted for 3 nights in Copenhagen. After that it was back to Berlin for a couple more nights before I left.

I had been to Munich and Bavaria before so I opted not to go there on this trip. I also went to the Münster area because my great-great-great grandfather came from a small town outside of Münster, and I wanted to see it and spend a few days there. That is when I rented a car since train and bus service was limited in the town.

What are your interests? Do you like history? Hiking and scenery? Those interests should tailor where you want to travel to.

You might look at various campgrounds to help,youndecide. For example in the middle Rhine, I know there is one by the river in Bacharach and one in Koblenz where the Mosel meets the Rhine. I met a couple who had stayed at one in Schiltach, a nice town in the Black Forest

Thank you all.
Going north is certainly a great option.
History and culture are my priorities, then nature. We have beautiful nature here in the US.

I will combine north and south.
I will avoid camping places as much as I can, since the van is 100% self sufficient.

Thank you all for your replies. :)

@Mignon
The videos are fantastic! Thank you so much.

I second the suggestion of the North. If you are into history and culture,, it is worth noting that northern German culture is less what people think it is and aligns in many ways more closely with Scandinavian cultures historically. Water is the key element in the north--history of piracy, the Hanse and sea trade, fishing, Vikings, etc. Far less about the Wurst in this part of the world--much more about the Matjes, Krabben, and Fischbrötchen.

I must say I know nothing of camping with a Wohnmobil here. I think the Region around Dresden and the Erzgebirge in Sachsen is worth some time. I would not skip Bavaria, Baden-Württemberg or a dip into Tirol in Österreich. Northern Bavaria (Franken) would be time well spent. Garmish - Mittenwald? Spring in the Schwarzwald? Be ready for your driving conditions on Autobahns and secondary roads.