If I can recommend you one thing in Vienna is to not waist your money on fast food! There are so many places in Vienna where you can eat very well for just a few Euros more than that you would have spend on fast food.  I really like the smaller family-owned places. If you like Italian food visit „Il Mare“ close to the Mariahilferstrasse. Make sure you reserve your seat, because it is always busy. Another place that I can recommend is the bright yellow „Siri’s Thai-Haus“ in the 20th district with waitresses dressed in traditional outfits. There is a nice inner garden where you can enjoy a lovely Thai ice-tea.

If you have some more time in Vienna, it is also very nice to take the train and visit some towns outside of Vienna, like Krems an der Donau and Stein. There are some good Heurigen, and locals also organize Weinfeste, where you can taste local dishes and drinks.