My son lives in Duisburg & we are hoping to visit at Christmas, looking into flights to Berlin or Frankfurt, any recommendations regarding Christmas markets in the North (Berlin) vs. the South near Frankfurt or the Black Forest? We visited him last summer & did quite a bit of travel along the Rhine but looking forward to seeing the festive markets in December. Thank you! ~
Erfurt has a very nice market. There are about 20 different markets in Berlin.
If you fly into Frankfurt, you can easily visit the markets in Mainz, Wiesbaden, Heidelberg, or Rüdesheim. Depending on the days you are here, there are beautiful small markets in towns like Idstein, Bad Homburg, Büdingen, Gelnhausen, or Seligenstadt, that are only held on one weekend during Advent, or just on weekends. If you have a car, then the market held on 3 weekends at Ronneburg Castle is a must. This is a medieval market held in a castle that is all original, located near Büdingen & Gelnhausen.
In general Christmas markets with a long tradition and without too many tourists, staged in a town not leveled in WW2, are the best. I'm not too fond of Berlin in this regard. Yes, Berlin offers more Christmas markets than any other city in Germany, but Berlin isn't exactly pretty, and I miss the "good old times" vibe. But if you're looking just for numbers, i.e. how many markets, how many stalls, Berlin is great.
If you fly into Berlin I would recommend to fly out of Frankfurt, and visit the area in between. Many German Christmas traditions, like Christmas Baubles (Lauscha in the Thuringian Forest), wooden Christmas decorations like pyramids, candle arches, nutcrackers or smokers (Ore Mountains in Saxony), Moravian Stars (Herrnhut in Saxony), or the Stollen (Dresden), come from Central Germany, the mountainous region roughly between Erfurt and the Polish border.
In this case I would recommend to see at least Dresden, and the previously mentioned Erfurt, and use Dresden to do a day trip into the Ore Mountains.
PS: here is a nice article about the Ore Mountains:
http://www.startribune.com/longing-for-light/110826984/?c=y&page=all&prepage=1#continue
If you make it towards Dresden and further to the Erzgebirge (Ore Mountains) the town of Annaberg-Buchholz has a nice small Weihnachtsmarkt. There are also many shops in the town that sell Smokers, Schwibbogen, Nut Crackers etc. This area is famous for this stuff. Good chance for snow in this region in December too.
https://www.annaberg-buchholz.de/weihnachtsmarkt/index.php
You could consider visiting Meissen (Porcelain, Christmas Stollen), Baytzen (everything mustard) and Görlitz (Görliwood, film locations) north and east of Dresden too. You would have to check the dates of the Weihnachtsmarkt in these towns. These are all good for 1/2 to a day visit.