I was on a long trip this past Spring, but I was on the move a lot and rarely stayed anywhere more than a couple of days.
From your list, I was in Paris, Budapest, Vienna, Prague and Nuremberg.
My tastes are extremely out of the mainstream in general, and I really don't like to drink, so I can't help with that aspect of things if it is what you seek. However, that being said, I'd recommend going to Munich and Berlin, which are much better street food places and not very far from where you already plan to go anyway.
I didn't find the food in Vienna or Prague all that great in general. Sorry.
Budapest was much better, since Hungarian food had a lot more flavor, and is probably a better deal now that their economy and currency have tanked. Remember that goulash is a soup over there, so have a porkolt if you want the stew that everyone calls goulash elsewhere. I don't know if they still do it in the wintertime, but they have some awesome cold fruit soups there. And, every pastry or dessert I had anywhere in town was great. It may not be what you want to do, but a very good sit-down restaurant, that is not touristy (bad food and "gipsy" violinists all in your face), and is right around the corner from St Stephen's, I'd recommend
Cafe Kor. I didn't go there, but there's also a restaurant with the interesting name of Marquis de Salade, and another place that serves huge portions called Fatal.
Nuremberg is all about roasted bratwurst.
Paris is so enormous, you can find anything, but it will cost you. I liked anywhere in the rest of the France far better than Paris.
If you still have time, it wouldn't hurt to go to chowhound.com, go to the international and/or France board, and ask what you're looking for. That's what I did before I left.
Good luck and good trip.
BleedingPurple
Central Europe - Must Haves 
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