Unfortunately, I haven't been to Christmas Markets in any of those cities, but here's a resource that may help you with your planning:
I was there last month (Dec. 2012) and went to some smaller markets and some larger markets in:
Those that I liked the most were in the small town of Schwäbisch-Hall and Vienna.
Schwäbisch-Hall was on a very small town square, and they had a small childrens' band play Christmas carols followed by a concert of two dozen or so Alphorns. Weihnachtsman (Santa Claus) walked through the crowd giving gifts to the young children. Very charming.
Vienna had several markets, and the one in front of city hall seemed to be the largest, but it was also very interesting and the decorations in the trees and park in front of city hall helped with the spirit. (The decorations throughout central Vienna were magical.)
Enjoy your planning.
I have been to the markets in Germany and Austria a number of times.
My choice from your list would be Berlin. Markets are good quality, there is much to do and see and the city is wonderful. It is one of our favorites in Europe.
Frankfurt is not our favorite but we had a nice visit last month to Mainz, easy to reach from FRA and quite charming.
Otherwise we prefer the smaller towns in Germany (Regensburg, Wurzburg, Bamberg) and Austria (Salzburg, St. Gilgen, Bad Ischl).
Munich also makes a good base.
Thanks very much both
My wife and I to Christmas markets also in 2012 (just 10 wks ago) time flys
Wurzburg, Bamburg, Rothensburg de tabor and Regensburg ( the princess castle Market not to be missed) were our favorites. Did find the one in Ulm very crowed but had an excellent time there also. Munich was a zoo downtown very crowded could hardly move in the evenings especially.
Did not care for Frankfurt but slipped thru there cause thats where our USA flight landed.
I am also planning a trip with Kids and grandkids (from Australia) and am interested in this tread.
Initially I thought it best to just pick one market and stay in the town for 5-7 days and explore the surrounds as well as enjoy the markets
We have two children (7 and 10) so do not want to move too often.
Is it likely that there may be snow anywhere in mid December?
In 2010, we had lots of snow in early December in Germany. Other years (over ten trips to the markets so far) it has ranged from none to a little.
Also had snow in November 2012 in Nuremberg, an almost blizzard. Mother Nature is not at all predictable.
This last year there were heavy snows in both October and November in parts of Germany. In most of Germany in December the temperatures will vary from slightly below freezing to somewhat above it. If you want snow, higher elevations are more likely to have it instead of more typical rain if there is going to be precipitation.
I have been to most of the major German markets and a few of the smaller ones. Personally I love the Frankfurt market. Yes, it is incredibly busy at weekends but it has such a lovely atmosphere to it. You can also jump on a train and visit Wiesbaden which is just half an hour away by train. It is much better than nearby Mainz. I would also recommend you visit Rhudesheim on your Frankfurt trip too. It offers a much smaller but very beautiful traditional market. In Frankfurt you have a major base with so many lovely day trips to other markets nearby. It is always my first choice.
Berlin doesn't have the continuos sprawl of a single market that places like Munich, Frankfurt and Cologne have. Cologne is lovely but ridiculously crowded. Other good markets can be found in Stuttgart, Dreseden and Nuremburg.
Out of the cities you listed, I have only attended the Frankfurt Christmas Market. It is wonderful. The market goes on and on throughout the city. Everytime you turn a corner, there is more. Beautiful and full of holiday spirit. Very crowded.