Traveling from Dresden to Salzburg

You could easily spend 3 of your 5 days in Prague, but by car, you may prefer to avoid the navigation and parking issues of the big city. At http://www.ricksteves.com/europe/czech-republic, see "At a Glance" for a summary of several other worthwhile stops, including a few cool castles and interesting small towns.

One little town right on your way is Regensburg. The old town sits on the Danube. It is a delightful city to walk.

The options are extensive. Here's some ideas.

Leipzig is one of my favorite cities in Germany. It won't take long to explore, but it's easily the most attractive city in the former DDR. It has one of Europe's best zoos as well.

In northern Bavaria, look into Bamberg, Coburg (best castle in Germany, in my opinion) and Nürnberg.

Moving further south, Regensburg, and if you have any interest in the Napoleonic period, Kelheim for the Befreiungshalle.

Landshut is a gorgeous Baroque town with an interesting castle, as is Passau.

Burghausen has Germany's largest castle and a nice old town.

Chiemsee, for the amazing view and Ludwig II's Versaille replica.

How's that for a start?

For nature, Königssee is beautiful. Park in the big pay lot by the boat docks, and just amble around the path between lake and mountain by foot, take a boat to the monastery, maybe a cable car up the mountain...