Now that DS is 3, DP has a hankering to take him to visit a Christmas market in Germany somewhere near Christmas. Think snow, mulled wine, pine trees, traditional romantic hand carved artisanal doodads and no plastic tat etc - I pointed out we have a German style Christmas market in our city but it's Not Proper. 
So, where would be a good place to go for a long weekend that has a good Christmas market and ideally isn't too eyewateringly expensive? We can fly to Berlin, Hamburg, Munich, Frankfurt & Dusseldorf easily, but am not set on those cities if there's anywhere nicer.
Any suggestions?