Tokyo to Sapporo via train and car – where to visit? And where to drive?

I am planning to spend about 7-9 days making my way from Tokyo to Sapporo via train and car (mixing it up based on what makes sense) to spend more time in regional parts of Japan, enjoy some nature, different towns/cities and cultures of Japan outside of the standard Golden Route but I am struggling to decide what areas to pick and where I can travel via car or train. I'd like at least some of the trip spent driving through some beautiful natural spots but honestly I am struggling to find what areas are best for driving and which should be explored via train or bus.

Any recommendations of itineraries/top spots I could consider, and what areas I could drive through v catching a train would be very much appreciated. The intention is to end up at Sapporo via the JR train.

Thank you!