There are a lot of places to visit in Germany. If you like history you can go to Berlin. There is the Brandenburger Tor, Checkpoint Charly, Sieges Seule (Goldene Else), Kuhführsten Damm, Mahnmal and a lot of other great things. Bavaria is a place with a lot of mountains and hills. There are old churches, nice landscapes, sauerkraut, beer, it's the typical german way of life you can see there. In the west (NRW , North Rhine Westphalia) , where I live, is a lot of industry. The Ruhrgebiet has a lot of culture. A lot of big citys are here. Dortmund, Essen, Köln, Düsseldorf, Münster and Duisburg. In the north of Germany is the sea. Also great. I have been in 2006 to the island Sylt. It's a small island whit a nice beach. Hamburg (also in the north) is also a very nice city.
The biggest cities you must visit are Berlin, Hamburg, Frankfurt am Main, München (Munich), Köln (Cologne).