Stuff from me
Germany
Def go to Berlin, awesome city. I agree with Spike, do the walking tour. It was the best introduction to the city and you get an amzing history that you just don't get walking around by yourself. If you are into museums go to the Pergamon (sp) - this is easily the best museum I ever been to, get the free audio tour. Also go up the dome of the Reichstag (Parliament) at dusk, the view is amazing. The Jewish museum is also interesting.
Hungary
I loved Budapest. Just wandered around Buda and Pest. Hungarians are so friendly and a couple took us under theer wing. Make sure you go to one of the Turkish Baths
Poland
If you are doing the hostel thing, stay at Nathans Villa in Krakow. Easily the best hostel in my travels to date. Auschwitz is also a must. Had some awesome nights out here.
Austria
Salzburg is stunning. Of all the old towns I have seen in Europe, theirs was the best. Just had a really nice time here sitting on the bank of the river having picnics. Sound of Music tour is kitsch, not sure if it is up your alley though haha
Czech Republic
I went to Prague and it was a bit ho hum, everyone else has loved it so take my opinion with a grain of salt. The constant rain and hungoverness due to the hostel bar may have had something to do with it
One of my highlights has been Croatia so I would highly recommend it. Truly stunning place. I spent time in Dubrovnik, Korcula Is and Hvar Is - Amazing!!!!!
If you want some inspiration check out my travel blog and photos - www.offexploring.com/laina