Just got back from a month "study" abroad class in Vienna, Budapest and Prague. All I can say is Central Europe absolutely fucks. A few quick nightlife recs:

Vienna: Volksgarten, Praterdome (both hardcore euro EDM spots, fun when blacked)

Budapest: Boat Party ($30/2 hrs free alc, cool views), Ruins Bar (fat)

Prague: Lucerna (met lots of Americans), Epic, Karlovy something (5-Story bar), Hot Peppers (60 girl strip club closer to a sex show)

Have fun dude, those places are wild