In early October, I am driving from Rothenburg ODT to Salzburg in one day and wondering if you could recommend 1-2 cool sites to see en route like a quaint village/castle for a lunch and coffee stop. Also later on in the trip doing another drive from Salzburg to Fussen and also looking for recommendations for similar historic sites to stop at , also a day trip. Thanks in advance, Laura
...a quaint village/castle...
Not sure of your route, but Pappenheim, in the Altmühl River Valley, is a fine little place.
https://www.frankentourismus.de/data/thumbs/img/8211913_christa-stadt-burg-3.jpg
Lots of other Pappenheim photos:
https://www.stadtbild-deutschland.org/forum/index.php?thread/5223-pappenheim-galerie/
https://www.tripadvisor.com/Restaurants-g1826152-Pappenheim_Middle_Franconia_Franconia_Bavaria.html
Weißenburg in Bavaria should be enroute. It is a really nice small town whose old city walls are still largely intact but turned into a park, and some Roman ruins, as it was part of the border fortifications back then. Near is Wülzburg fortress (not a medieval castle but an early modern fortress). https://www.weissenburg.de/ Is only in German, but maybe you can try auto translate.
Eichstaett is a small town with an old but impressive castle, now a palaeontology museum with a specimen of proto bird archaeopteryx as its most important feature. The town itself is nice, too. https://www.eichstaett.de
Just head down the Romantic Road, which has several medieval walled cities as well as Augsburg, a historic city over 2000 years old.
The Romantic Road ends in Fussen.
https://www.romanticroadgermany.com
It's not too hard to see the reason for the popularity - despite the modern roots of the idea, the tour combines the historic cities of Würzburg and Augsburg with the three medieval walled towns of Rothenburg ob der Tauber, Dinkelsbühl and Nördlingen, and then finishes off with the tourist highlights of Neuschwanstein Castle and the Alps.
l-b_m has wisely suggested Weissenburg and Eichstätt, which lie near each other as well as near Pappenheim. These two are also charming places to visit, either by car as you are doing, or by train, as I did. You could pretty easily make your way to all 3 of them in the course of your day.
The area is easy to overlook for outsiders. Customers on European river cruises that use the Main-Donau Kanal skip right past it. Rick Steves, whose materials tend to cover routes and destinations that are oriented more to international tourists rather than places where Germans and other Europeans tend to recreate and vacation, does not address the above towns or the Altmühl Nature Park, where they are located. And that is just north of Ingolstadt and the Danube River. See map:
http://www.das-altmuehltal.de/altmuehltal-karte.png
The site below may be helpful in gathering more information. Click on "exploring" then "places of interest."
With a car? I'd head to Wornitz (A7) then cut across to Donauworth on 25. You'll pass through Feuchtwangen, Dinklesbuhl, and Nordlingen while traversing a meteor crater (museum in Nordlingen) and cutting through the Swabian Alps. Take Rt2 down to Augsburg and pick up A8. Then take 99 around Munich to 304 to Prien am Chiemsee. Then pick up A8 again and head east to Salzburg. Not the fastest route, but a heck of a nice drive. I'm partial to Nordlingen and Chiemsee so those would be my stops. But there's a lot to choose from on that route. A lot of folks would recommend Dinklesbuhl, but I think it's just too close to RodT for a first stop. It is a very pretty town though. And Augsburg is always worth a stop.