I love Europe, and I spent about two years hitching, wild camping, and a bit of volunteer work there. I spent most of my time in eastern europe, though, and i'd love (and will) go again. The people can take some getting used to, and just because they don't smile much doesn't mean they aren't nice and helpful, because they are! The food is awesome, the landscapes beautiful and not as industrialized as much of the West, it's cheap for just about everything, hitching is easier, and there are so many abandoned buildings.
I'm not city guy, but Budapest was lovely. I also ended up working on a farm a wee bit south of budapest, which was on the outskirts of an abandoned Russian base and also had basically a little abandoned village all around me. I could squirrel through gaps in doors or windows and be in places stuck in time from the Soviet days. Even found an old officers cap with the red star on it, still.
Romania and Bulgaria I spent a couple weeks in each, but would really like to spend more time there. I can't quite place it, but those countries have that old feel to them that I always imagined about Europe in general would be like (in my fantasies, that is).
I MIGHT end up going there again soon, within a month or so. I'm still not sure myself. It's either South America, or Eastern Europe
Also, Budapest has an awesome folk/metal/punk scene. Check out Durer Kert, a university campus turned into a huge music venue. I recall a death metal festival, where they had different rooms for different bands going at the same time.