Hi Cyron, I have to agree with Robert: It depends.
Where are you going to be located, how much time do you have, what season (summer is not the best time, indeed), what type of transportation will you use and most importantly what are your interests?
Germany covers quite a range of different types of areas from the costs in the north, through flatlands, high moors, mountain ranges, different types of wooded areas, river landscapes...and of course all sprinkled with the castle on the hill (or castle in the meadow) type of spots, if you like that. Also, keep in mind that Germany is densely populated and most if not almost all landscapes are essentially man made: Agriculture, forestry - there are only a few areas converted into natural parks.
So, what will it be?
I live in the South-West of Germany, in Heidelberg.