What are the positives/negatives of driving in Germany
When I traveled for business in Germany, people from our sales office would chauffeur me around by car, and I have driven in Germany, but today, on my own, I by far prefer to travel by train (or bus). I find the flight over and back to be a strain; I only endure it to in order to be able to experience things I can't experience in the United States, like eating authentic German food, trying to converse in German, and traveling on really good, efficient rail transportation. So one of the negative things I find about driving in Germany is that it is the same old thing that I do (have to do) in the US.
If I lived in Germany and already had a car to use it would be one thing, but I find renting a car in Germany to be more expensive than using public transportation. Before every trip I've taken in the past 10-15 years, after I've settled on an itinerary, I've compared the cost of a rental car (rental and gas) for my trip to the cost of train tickets and I've always found the cost of a car to be 2 or 3 times as expensive as using public transportation. If you take the time to learn how to use the rail system in Germany, and how to get good prices on tickets, it can be very economical.
Lastly, at least for the driver, driving means having to watch the road and not being able to fully enjoy the scenery. In a car, the seats are relatively small and confining, and you have to stop anytime someone wants to eat or use the bathroom.
I have never had a problem finding suitable accommodations within a short walk from a Bahnhof or easily accessible using public transportation or taxis.
Using a car to get places in Germany can, at times, be faster, but you have to offset that with the fact that, particularly for the one driving, you have much more freedom by rail vs car as to what to do with your time.
By the way, for your trip I might recommend staying in Oberammergau. From O'gau you have bus connections to Garmisch-Partenkirchen, Linderhof, and the castles at Füssen, and a rail connection (through Munich) to Herrenchiemsee. For Oberammergau, I would recommend staying at Gästehaus Richter. It's nice, close to the rail/bus station, reasonably priced, and Frau Richter is a gracious hostess who speaks good English.