Try the city's website: Vienna - NOW or NEVER
The cafe piano music is a traditional pastime for the Viennese. The acoustics of the Musikverein are outstanding; if you can get a seat stage left--on the big stage--for any kind of concert, I'd highly recommend it. Peterskirche has a great organ/environment and free concerts that are great. Music is all around...you may want to experience the different acoustic spaces around the city.
For food, I would HIGHLY recommend Dom Beisl (slightly more viennese) and Mraz & Sohn (slightly more Austrian). If you want to know what a Wienerschnitzel should taste like, go there. However, these are artist chefs, so I order their tasting menu. I go to Dom Beisl a few time a week and Mraz & Sohn at least once a month when in town...I rarely go elsewhere. A 4-course lunch at an outside table at Dom Beisl, and a 9-course dinner at Mraz & Sohn's kitchen table is what I like to do. Make reservations, and do the wine pairings. Both Sommeliers are world-class at pairing the wines with the foods. If you are looking for a viennese breakfast--and the finest croissants imaginable--go to Orlando di Castello BEFORE 10am! Make a reservation and sit outside.