Hi. For sure you are choosing one of the best places to come on your first time to Europe.
Let see. Wien is awesome, it is very nice and it has lot of things to do, however it is very expensive but it worths it.
You have to see the palaces and the cathedral (stephansdom), if you are into classic music don't miss the Vienna's boys choir.
The most typical thing you can it eat there is the sachertorte and if you go to the sahcer hotel, it is going to be the original one.
Don't forget to try Grüner Veltliner, is a very good wine.
And if you are in Wien I will recommend you to go to Bratislava, you can take the train which is very cheap and you will be there in less than an hour. The city doesn't have to much to offer, but it is very cheap so you will spend a day eating and drinking for the tenth part of what you would pay in Wien.
If you go to hungary, which is definetely my favorite place in the imperrial triangle, go to Budapest, is a lovely city and the prices are very goo too. Food is ok, but I will recommend you to go to the market and ask for the gülash.
Reserve one afternoon for the bath in pest. I dont remeber the name but they are the most famous and there not so many tourist, cause they are send to a hotel which is very famosu too and much more expensive.
If you don't see the parliament, is like never been there, so once again, don't miss it.
Now prague, you wont find a city in eastern europe with more tourist than PRAGUE, and that is beacause the city is very nice, so full of history and dowtown is great. The best thing you can do in Prague is drink beer, the best beer you will ever taste is call budweiser budvar, which is the original budweiser. If you like dark beer ask for it, better than guinnes and better than leffer.
If you go to Germany, specially the bohemian part, try to go to Salzburg which is 1 hour away from Münich and you will see Mozart's city. Münich is also very good you have to go to a biergarten and ask for a mass which are the beers of 1 liter and drink it with a pretzel or chicken. Now, if you have spent too much money, go to the turkish area and ask for kebab, they are even better than in Istanbul.
And finally if you to Berlin, well try to see everything except the jewish museum, which is actually not much to see and it is expensive.
There thousands of pubs and discotheques in Berlin specially if you like house and techno.
One last thing, if you go to salzburg, try to go to mathausen, which was the third biggest concentration camp, It will give you a pretty good idea of what happened in that time. Mundseen, is a lake very close, actually is a lake area, and you won't be disspaointed