I’ve been to all those cities and it sounds like a good route in that you aren’t backtracking—the circle route is a good way to go! ;) I have been to all these citiesand really liked them all. I would leave some flexible days, though, because there are some smaller places between these places that you can see and it’s always nice to have the flexibility to add something in later if you meet someone who makes a suggestion along the way.
Side trips could include Cesky Krumlov near Prague, Salzburg in Austria, Interlaken in Switzerland, Nice or similar in south of France, Cinque Terre in Italy, etc. It’s nice to see smaller places along with all these big cities—the only smallish city you list her is Bruges (which is beautiful.)
Let me know if you’d like some more suggestions!
Jennifer, gwu@statravel.com, 202-747-9772

Brugge is amazing! i loved it so definatly have fun while you are there other than that if you are not claustrophobic you can go spelunking(caving) in Budapest and that is amazing and not to expensive and definatly worth it. I think it is a total of 3 hours that you are in the caves and you can find information on Caving at most hostels if you are staying in any. When you are in london be sure to hit up the Tate modern, it is an awsome museum and has great views of the City from the balcony there. All the museums there are free except for some special exibits in the museums.