Driving from Germany to Austria
 

My family (including two teens) is visiting Amsterdam, and then traveling to to Heidelburg (1 night), Rothenburg ob de Tauber (1 night), Salzburg (2 nights), and Munich (2 nights). We are driving from Rothenburg ob de Tauber to Salzburg in one day. Should we take the Alpine Road? Stop along the way (and if so, where)? Or hurry to Salzburg and then see those sights?

We like walking, hiking, biking, boating, visiting castles and museums. More interested in architecture than the furnishings of castles/palaces. We have all of the guidebooks but are finding them to be overwhelming.

Go directly to Salzburg. You have not time to stop en route. The obvious intermediate stop would be Munich but you are visiting it anyway. Another obvious stop would be Herrenchiemsee castle, but you need time to visit it and I am not sure you really have it.

I'm also trying to sort through the ton of information about Germany in tour books and websites (mainly this one). I'll be interested in the replies you get.
We are definitely taking the time to see Herrenchiemsee castle. Many people recommended that one or Linderhof (out of your way) and agreed that King Ludwig's castles were worth the stop. Good luck with your plannning!

Given your itinerary, I would agree with asps. Every town along the way has "something" that "someone" will say is a "must-see." Even the Alpinestraße can compel a traveler to stop for no reason other than to enjoy its beauty. Motor directly to Salzburg (don't forget your Austrian vignette) and enjoy the couple of days you'll have there. Save the rest of Bavaria for a return holiday.

If they are just going to Salzburg and stay there they could exit the highway at the Piding-Bad Reichenhall exit and go by ordinary road to Salzburg sparing a vignette for a few kms. The important thing would be never use the higway around Salzburg or do day trips on Austrian highways. When they are going back direction Munich there is an hidden bypass to the highway already in German territory (no vignette): just take the road from the Salzburg airport to Wals and Walserberg, as soon as you cross the border there is an entrance to the highway direction Munich.

asps, I like how you think. We take the local roads from Vienna to Bratislava to avoid the Slovakian vignette. But, as holiday travelers, we'd more than likely pony up the €8 for a vignette for the peace of mind, especially if doing so avoided hidden bypasses on unfamiliar roads. ;)

Thank you, everyone! I assume that the vignette is a toll? Is it like the tolls on U.S. roads or is there some reason other than cost to try to avoid them?

Make sure your rental company knows you are going into Austria. Ours provided the vignette.

The best advice for a trip to Germany is to enjoy where you are instead of trying to see too much.

Yes, the vignette is a toll, and there are numerous places to purchase the sticker in advance of the Austrian autobahn. The minimum Austrian vignette is good for 10 days and costs €8,30 (there are no day vignettes). Some car rental companies provide the vignettes, others do not.

Another, less crowded route than via Munich would take you first East to Nuremberg on A6, then SE on A3 to Regensburg.
Which would be an excellent stopover to visit (with or without the Palace).
Then continue on A3 until you get in the vicinity of Straubing where you hit B20.
Take B20 South till you get almost to Salzburg near Laufen. Cross the river and drive into Salzburg on the Austrian side.
B20 will take you via Burghausen which has a magnificent castle, the biggest castle "complex" in Europe actually.
Timewise you could do either Regensburg or Burghausen, but probably not both unless you keep a limit on your visit of Regensburg.

There is so much to see in and around Salzburg, you will regret having just 2 nights. Be sure to go to Mondsee to see the church where the wedding scene was shot in Sound of Music. So I would drive straight there. I drove Rothenburg to Salzburg once in 4 hours but it was really early so there was no traffic going through Munich and I never got below 190kph.

It sounds like yiu are a little cramped fof time at the backend of your trip. You might consider dropping Heidelburg ang going straight from Amsterdam to Rothenburg. The little road like the Romantic Road is name by some PR guy. It is romantic because it goes throught some charming towns. You can take the autobahns and save a lot of time. This is beautiful country and it is full of charm. Have a great trip.