Maybe a 'short, sharp trip would be more palatable to him. We were there for 6 weeks so there was plenty of time for the cold to get into our bones. A trip to a couple of the more famous ones like Nuremberg and Dresden or Strasburg and one or two smaller markets might be enough. Apart from the markets we also caught up with four lots of friends so our trip was a bit more extended. Hopefully D Bahn might even be running properly in the future - if Germany gets over the current rolling national strikes across the transport sectors..