Frommer's has a one-week itinerary for Austria: two days in Vienna, two days driving in the Danube Valley and Lake District, and two days in Salzburg (plus a day in Innsbruck, which I'll be skipping). Sounds reasonable, though I'd more likely take the train than drive (high rental and gas prices, and I don't drive stick). Their 3-day Vienna tour has a mix of this and other stuff.
- Day 1: You can skim the highlights in just 2 days by concentrating on St. Stephan's Cathedral in the heart of the Inner City (Old Town). Climb its south tower for the most panoramic view. Later that morning, visit the once imperial Schönbrunn Palace, summer seat of the Hapsburgs. In the afternoon call on the Hofburg, visiting its major attractions such as the Kunsthistorisches. In the evening take your choice: an opera at the Staatsoper or a night spent in a raucous Viennese wine tavern.
- Day 2: take in the glories of the MuseumsQuartier Complex, paying particular attention to the Leopold Museum and the Kunsthalle Wien. Attend a performance of the Vienna Boys' Choir at the Hofmusikkapelle. Try for an afternoon visit to the Belvedere Palace and its fine art galleries. For a typically Viennese experience, spend your final night at one of the wine taverns on the outskirts of the city. They are called heurigen, and some of the best of these taverns are found in the suburb of Grinzing.
- On Day 3: head to Salzburg in the car you rented in Vienna. We suggest a 2-day leisurely journey with stops in the Danube Valley and in the lake district of Salzkammergut. Instead of the Autobahn, take Route 3, called the "Austrian Romantic Road," west from Vienna. On the north of the river you can follow this lovely old road into Krems, 80km (50 miles) west of Vienna. You can use Krems as a base and set out on two side trips; first to the old wine town of Dürnstein, 8km (5 miles) west of Krems, then to Melk Abbey, 31km (19 miles) away. You can double back along the road leading northeast into Krems for the night, or you can also select Dürnstein for an overnight stay, as it has even better and more romantic hotels than Krems.
- Day 4: leave Krems and drive south to the Autobahn (E60) that runs west to Salzburg. At the junction with Route 145, head south into Bad Ischl, your best base for touring the Salzkammergut. The driving distance between Krems and Bad Ischl is 224km (139 miles). Check into a hotel in the fashionable spa of Bad Ischl and stroll its Esplanade. You can see the Kaiser Villa where the emperor lived for 60 summers. If time remains, you can also check out Villa Léhar where Franz Léhar lived in 1912. After lunch, drive down to Hallstatt, 19km (12 miles) south of Bad Ischl, where you'll discover one of the most beautiful villages in Austria. It stands on a narrow lake, the Hallstättersee, and requires about 2 hours to see. Northwest of Hallstatt you can visit the Salzwelten/Hallstatt Salt Mines, one of the most distinctive geological formations in the district. Return to Bad Ischl for the night.
- Day 5: leave Bad Ischl following Route 158 west into Salzburg, a distance of 56km (35 miles) and our base for the next two nights. After checking into a hotel, set about exploring the second-most fascinating city (after Vienna) in Austria. Sit at a cafe on the Mozartplatz for a coffee and a pastry before taking the funicular to the Hohensalzburg Fortress for a tour. After lunch, you can see Mozart's birthplace on Getreidegasse. Allow time in the afternoon for a visit to the Residenzgalerie, the opulent palace and former seat of the ruling Salzburg prince-archbishops. If the Salzburg Festival is taking place at the time of your visit, plan to attend some cultural offerings -- certainly Mozart's music -- in the evening.
- Day 6: set out to see the sights you missed the day before, including the Dom or cathedral and Stiftskirche St. Peter, as well as Petersfriedhof, the cemetery of St. Peter's. Wander through the Mirabell Gardens, and spend at least 2 or 3 hours in the Altstadt, the Old Town, where you can shop till you drop and take in the antique buildings.
Instead of driving, I'd take trains between the different towns. To get from Vienna to Krems requires a quick transfer in St Poelten first. There don't appear to be trains from Krems to Dürnstein but there are probably buses. To get from Krems to Melk, though, I have to go back through St. Poelten, a 90 minute trip. If I'm going to end up in Krems for the night, to avoid backtracking I'd do Vienna to Melk via St Poelten first, then Melk to Krems via St. Poelten, get a room to dump my stuff off, then take the bus from Krems to Durnstein and back for the night. This map will make more sense. I'll put down the 7:40am to 8:49am Vienna to Melk run, then the 12:57pm to 2:24pm Melk to Krems run.
The Krems to Bad Ischl train ride has two transfers, one at St. Poelten (again) and one at Attnang Puchheim. The most reasonable one is the 8:37am to 9:18am Krems to St. Poelten, then the 9:28am to Attnang Puchheim arriving 10:58am, followed by the 11:19am train to Bad Ischl, arriving 12:21pm.
The train from Bad Ischl to Salzburg leaves 7:35am and gets in 9:49, with a transfer in Attnang Puchheim.
So for the sake of pre-planning the itinerary, I'll mark this one down as 7 days - days 25-31, though of course that's flexible. And that includes one day off. Here's my entire Austria train itinerary from Vienna to Salzburg.
The train from Salzburg to Munich runs about once an hour, and takes between 1:30 and 2:00 to get there depending on which train line and how high speed it is. I can do, for example, a 7:51am that gets in at 9:33am.