This summer i visited: Hungary (Budapest), Austria ( Wien, Salzburg and Innsbruck ), Germany ( Munich, Stuttgart, Rust-Europe Park), France ( Strasbourg )
Budapest it's nice, but it wasn't very impressive for me.
Wien it's very beautiful, really liked it. You should visit Schonbrunn palace and city center.
Salzburg it's very nice. Worth visiting the castle.
Innsbruck it's awesome. I liked it because of the mountains.
Munich it's a very modern city. I was surprised by the luxury cars i've seen there. Very good one to visit.
Stuttgart, only spent a few hours only, so can't say an opinion.
Rust- Europe Park - awesome, awesome, awesome. This was definitely the best decision from my trip. I stayed there for 2 days, and i loved it. The park it's really big, and one day it's not enough to see and ride everything. I was really scared on the roller coster "silver star" (search on youtube to see why).
Strasbourg is a very small city, but modern and nice. I visited at 6 PM, for a few hours only, but i was surprised that there was almost nobody on the street. Very few cars, and people on the street, i wonder what they were doing.
I liked Austria the most because of the beautiful Alps.
I plan to visit next year: France (Monaco,Paris), England(London), Spain (Barcelona).
About the countries you are interested to visit, i can tell you about Romania. The roads are terrible, the rail ways also. I would recommend you to come and visit by airplane only. If interested in Bucharest, you should visit this:
the house of the parliament
the village museum. Very interesting, you would love it. Lot of cool things to see.
Athenaeum of Bucharest
Now, other places in Romania, check this video.
[ame=http://www.youtube.com/watch?v=ip_QZaBfXqM]Wild Carpathia Trailer featuring HRH The Prince Of Wales.wmv - YouTube[/ame]
where TOP GEAR said it's the best road in the world:
[ame=http://www.youtube.com/watch?v=cmmij7KqC4o&feature=related]Transfagarasan - versantul de nord - YouTube[/ame]
also
Peles Castle