Can I visit Salzburg (sound of music tour) in the winter? Are there any amazing trips/places to see when I'm there 18-22 December?
You can visit Salzburg any time. The Sound of Music tour only operates in the summer, weather permitting. There is a Christmas market, also concerts and Christmas-themed events. Some years there is a lot of snow at Christmas.
Nothing to do with Schönbrunn. Suggest you Google search on the Salzburg sound of music tour.
Not sure the relationship of this question/s to Schoenbrunn Parkhotel. Vienna & Salzburg are about 2-3 hrs train trip apart.
Never been to Austria in Winter myself so can't answer the specific question. Of course there are many amazing places to visit in Vienna any time of the year, look at Tripadvisor Vienna forums for some tips.
Get an answer from Austria Trend Parkhotel Schoenbrunn Vienna staff and past guests.