If you need anything or wish to pay, you must flag them down. There are numerous dessert choices. Sacher Torte is everywhere, but you can only get the original at the Sacer Hotel in the first district. Aida is a great commercial pastry shop, but don't miss the small hometown bakeries for Apple Strudel. Buying one cup of delicious Viennese coffee entitles you to stay for an hour or two.
Most cafes have local and international newspapers for the patrons to read.