this was just discussed a couple days ago - do a search - most of the best markets close down Dec 23-24. We go over every other year. The ones that do stay open are scaled down and many vendors are gone. Vienna and Prague do stay open, do a Google search for dates - it's easy to find. And find the post from a couple days ago. Also, 2020 markets were canceled in Oct, so we aren't even sure yet if the markets will happen in 2021 (although we are certainly hoping, as we are going Nov 26-Dec 11). Dachau is an easy day trip from Munich, but the Munich markets aren't very good and they will be closed. Lots of info on these forums. Also, book MULTI-CITY flights, fly into one city and out of another so you don't have to circle back. You can always fly out of Munich and do Dachau then. We've used Radius Tours (as recommended by Rick Steves, and we've also done a Private Tour with Big Hat Tours which was fantastic. Salzburg markets will be closed, but it's still a great city. Maybe stick with Prague, Salzberg, Vienna, Munich. We never rent a car - the train is super easy - we book 6mo out to get the best price.