I have a friend in Berlin where I've studied abroad before whose place I can stay at for free. I've got two weeks of vacation time I can use for this trip and am trying to taste a couple of other cities. I enjoy Berlin and was thinking I could fly in and of there with some train trips in between (saving money the nights I stay there). I've had a couple of ideas to possibly take a train to Amsterdam and then hit Cologne and another west German city. I know I could also stop somewhere in the north of Germany between them possibly Hamburg. Or I've thought about going down into the south possibly stopping in Prague and going into Austria.
Any advice or insight into either of these ideas would be much appreciated. I'd be traveling from Berlin alone and am a young person interested in sight seeing during the day, but am looking forward to experiencing some fun night life.