Hi there,
As you only have seven days to experience Germany and
Austria, I would structure the 7 day trip as follows:
Day 1 - Arrive in
Frankfurt on the 4th-5th August.
Staying at the Marriott Hotel. Visit the Imperial Cathedral in Frankfurt and some museums.
Day 2-4 - Stay three days in Heidelberg
Catch a bus from Frankfurt to Heidelburg (around an hours drive) from Heidelberg to Baden-Baden.
Visit the Universitätsplatz and the old universityCruise, the Alte Brücke (old bridge) and Brückentor (Bridge gate), Haus zum Ritter (Knight's house - the oldest private house in Heidelberg), etc.
From here, you can cruise the Neckar River towards the state of Baden. Once in Baden town, you can visit the Black Forest and some of the fine
vineyards there.
Day 5-7 - Visit Austria
I would allow at least three days for the visit to Austria to see Hofburg Palace, Ringstrasse, Kaertnerstrasse, St. Stephen's Cathedral, Schoenbrunn Palace, the catacombs below St. Stephens, etc. Try to spend as much time as possible there in order to soak all the wonderful sights.
Day 7 - Fly back home
Hope this helps
VacationBuddy