Yes I took a night train trip from Vienna to (I think) Göttingen (final destination was Kassel) last year and was able to have a single compartment with bathroo

Yes I took a night train trip from Vienna to (I think) Göttingen (final destination was Kassel) last year and was able to have a single compartment with bathroom all for myself. It was pricey but not pricier than a flight from Vienna to Frankfurt and then a train from there to Kassel, because low-cost airlines don't fly this route.