If you choose Nürnberg I can recommend the Adina apartment hotel. We love this chain because there is a kitchenette and a washing machine/ dryer in every room. We thought the location was very good, with restaurants and a grocery store close by. We did a walking tour with a historian that was superb. I know Munich also has an Adina, but we have not yet stayed there. We love Munich and have used it as a base during several trips. From Munich we have made day trips to Bamberg (where the smoked beer is famous), Salzburg, Regensburg, Kufstein,etc
We spent a few nights in Rothenburg, and found it very touristy. Kind of like staying at Disney, with similar mediocre, overpriced restaurants. The night watchman tour was fun. Even so, Rothenburg is probably our least favorite of all the places we have been in Germany. We have not stayed in Salzburg, but have visited it many times.
I would focus on what your preferences are based on specific interests- history, museums, food, music, nature, etc. Then pick a base of operation that makes it easy for you to get to locations that match those interests. Public transport is comprehensive and organized, so no need to have a car.
We have made many trips to Germany and Austria. Some of our first experiences were in Bavaria, but the northern cities ( Berlin, Dresden, Hamburg, Hannover, Bremen …) are also excellent. Then there are the Rhine villages for true relaxation. And lake areas like the Bodensee. And…
For your next trip right? 😊.
Have a wonderful trip, and embrace the RS motto of “ assume you will return”.
https://www.adinahotels.com/en/apartments/nuremberg/?utm_source=googleplaces&utm_medium=organic&utm_campaign=hotellink&utm_content=adina-nuremberg