Germany would most certainly be cold, but the trade-off is not dealing with crowds or lines. I tend to be over every year in January or February, and will be back again this January on a $467 fare.

One thing you should consider is rail travel. You could easily do some of Germany, add on Innsbruck and Salzburg, which can be gorgeous in the winter, or even Vienna. Maybe start in Germany and head home from Austria.

I have quite a substantial photo gallery from both countries linked below.