South Germany is really awesome, the people are friendly and in general the climate is nice.
Ultimately my favourite place in Europe is southern France, I spent a month living there with my family last summer and we lived in a tiny stucco house in St. Remy de Provence. It's ALL Roman settled area and the history is incredible. If you can speak french, its a really nice accent, and easy to understand (not like in the north). Food is garlic-y, warm and the wine of choice is Rose. In general though, its HOT all the time, like a desert and the cicadas are killer loud. Every little town has its own history and trains can take you wherever you want.
I also reccommend going through the valleys of the swiss alps into those small towns, more specifically Sierre (about 30 mins from Zermatt), Bitsch (a real place, google it), Meiringen, etc. If you want mountains: INTERLAKEN, Switzerland...take the train to Lauterbrunnen, where you can then from there take the mountain train THROUGH the mountain to the Jungfrau (highest observation point in europe i think). Its an incredible incredible place. The town of Wengen (on the way up to the peak) is so cool - no cars in the whole town. Cows much by the traintracks and this is really what Switzerland is like. PICTURE I TOOK (this is the real view from the train)