I went to school in Vienna & have created a word doc with things to do etc (not specific to around the holiday times). If you'd like a copy, direct message me with your email address and I'll send it to you. Also, you might want to check out the Europe forum on Flyertalk & ask there or do a search, as others have gone to Wien during the holidays. Maybe even in the Marriott forum on FT. A friend of mine was there during the holidays & it's quite lovely/magical. You'll enjoy it then. Not sure you're into formal balls, but usually those are also happening around that time.