I have a client near Braunschweig and always enjoy that market. Must do as I've been visiting every year for 21 years now. The Gent market is also good and if you've never been, you will be happily suprised how lovely the city centre is.
Me and the girlfriend went to Basil in Switzerland last year which was brilliant! Loads to see. We climbed a couple of churches/cathedrals, drank loads of mulled wine, ate loads of food, bought some toot and went home
Spent Christmas in Prague last year, which was lovely. Lots of Christmas markets, but with a genuine feel, as opposed to being naff. Lots of roasted chestnuts, mulled wine, and if you are lucky also snow.