I like Sunday mornings in Germany because they're very quiet. It's the ideal time to take pictures without crowds of people getting in the way. That being said there's usually someplace open, coffee shops usually, but most places that do open Sundays don't until around noon. Churches being the major exception.
The Pegnitz river flows up from Nuremberg thru Bamberg, where it joins the Main (which then flows to Frankfurt). The walk along the river through the old part of town is really nice. I think it would make a really good way to spend a day just walking around.
Many years ago I used to go there quite often as I had a friend who's father owned a Gasthaus. Bamberg is a University town and was good for meeting girls.
In Munich, provided you're not tired of museums, you can go over to the area by the Alta Pinokothek (Old Art Museum) and have your choice of that or the Neue (New Art Museum), the Modern art museum, the Crystal Museum, the Egyptian Museum, and several others. While I like those the engineer in me prefers the Deutsches Museum on it's own island in the river. If the weather is good I suggest a walk through the English Gardens or along the river. If you must do the beer garden thing the Hofbrauhaus is over rated, try the Lowenbrau or Pauliner ones (although if you're doing Octoberfest you may want to pass.)
Not knowing how long you'll be in Salzburg I'll only say this; you can easily spend a couple days walking around the old town and sticking your head into all the neat places. The fortress alone is half a day. But if you have the time you can walk around the hill the fortress is on and into a much less tourist visited part of the city. If you like plants or nature, the Botanical Gardens and the Kapizunerberg (across the river from the fortress) are nice.
