Of about 25 countries visited in Europe, Vienna and Krakow remain my favorite. One can easily spend a week in Vienna especially if you like Museums, Palaces, Opera, Cafe, etc. Bratislave is easy and inexpensive train ride (make sure to go to Castle for great view) Although it is inexpensive, I was bit uncomfortable at off peak hours. Got more sense of Soviet Union in Bratislava then I did in Warsaw.

I did day trip to Salzburg from Vienna and overhead of 5-6 hours travel time was bit too much. Salzburg is beautiful and special attractions to Sound-of-Music fans but I would have preferred to do it either leisurely with an overnite stay or as a quick stop while driving from Munich to Vienna/Linz.