Amazing photos! Last year I have visited few Xmas markets in Dusseldorf and Cologne, and they were awesome. Unfortunately, I don't have so many great pics like you. I hope you tried Reibekuchen (it's something like fried pancake made of potato and onion). I've never tried that anywhere before.
But if I need to choose one memory from this trip of mine, it would be a bunch of Santas who drove their motorcycles around the Xmas market in Cologne. It was really an awesome scene.
Many thanks for sharing these photos! Cheers!