Itinerary for a one week rail tour of Germany

Hello, after my language course in Berlin I plan to spend about a week travelling in Germany via DB. So far the only cities I've been to aside from Berlin are Leipzig and Hamburg, so I feel I need to see more of this country before I return to my home country. One condition being that I have to fit in the city "Jena" (wherever that is) somewhere because I must attend a concert there by this band, aside from that I am quite flexible. Since Jena is close from Dresden I plan to go there as well. Where else should I visit? If you had to pick 2 or 3 cities in Deutschland for quick and easy trips where would those be? I've been checking the bahn site and I can get to most places at 29 Euros one way, with the exception of Munich (i.e. travelling out of Munich and going to Koeln for example costs me 49 EUR whereas most other cities I've randomly checked offer 29 EUR fares, regardless of the distance)

Any input appreciated,

w.

It depends on what you want to do (party, sightsee, relax...) and when you have to be in Jena.