Hi (Just ignore that last arsehole - some people really need to get their heads checked out). .
You have got a great itinerary lined up there but if you think its going to cost you USD2.2k then you are sadly mistaken!! You're going to have to find yourselves a lot more money!!
Anyway, yes there is HEAPS to do in Paris. Sacre Couer is gorgeous, The Champs Elysses is great as is The Louvre and Musee D'Orsay on the other side of the Seine. Be sure to take the lift to the top of The Eiffel Tower and pay a visit to Hotel D'Invalides (Napoleans Tomb) - its the huge monument with the domed roof (you can see it from the top of the tower). . Prague to me is the most beautfiul city in the whole world. Be sure to spend a day at Prague Castle and visit the National Museum in Wenceslas Square in the old town. Also, you must visit St Nicholas Cathedral in the Little Quarter - its stunning. Other than that just stroll along Charles Bridge and hang around in the Old Town Square - have a Mexican Coffee for me at a cafe there called "Hotel U Prince" in the Square. Divine!
Krakow is beautiful and yes you should definitely try and catch a train or bus to Auschwitz. Take plenty of tissues. You'll feel totally depressed when you leave but you'll shake the feeling in a day or two.
I only spent one evening in Brussels but I recommend to you to catch a train to a little town an hour or so away called Brugges. It is delightful and the chocolateries there are divine. You can go on brewery tours there and theres lots of little clubs and pubs there. We filled up 3 days here.
As the last person said (not #@#%$%, but the other one), Berlin is not that great but its worth a day or so of your life. The Berlin Wall Museum is really interesting and its right next to Checkpoint Charlie so its all very historical. For a great view over Berlin catch a bus to the golden angel column (forgotten its proper name) - you can climb to the top, its great. Check it out in a guide book so you know what you're looking for.
Budapest is gorgeous and very hip. We stayed in Pest but we spent most of our time on the other side of the Danube in Buda where the old town is. We caught Europes oldest railway line to a Palace on the outskirts of Budapest (cant remember the name now) and went to a Museum back in the city. The people here are really friendly and its all very cheap. MAybe you should try and take a boat ride down the Danube.
Vienna isn't that great. If you're going to Austria you should head straight to a place called Salzburg - it is brilliant. There is heaps to do here. If you do go there you could take a day trip to Innsbruck which is just as beautiful and has a zoo and lots of cafes and is surrounded by the Alps.
Rome - god, there is too much to write. The Colosseum, The Forum, The Trevi, The Pantheon, The Vatican, The Spanish Steps, The Catacombs, etc, etc, etc. Just move fast because you wont fit it all in.
Sorry, havent been to Milan, Amsterdam, Ireland or Scotland. You will love London. It rocks. Again, there is too much to write but yes, check out the Palace, Trafalgar Square, grab a coffee at the Starbucks in Picadilly and just sit outside and watch the world go by, go to St. Pauls Cathedral, The Tower of London, etc, etc, etc.
You're going to some great places so enjoy. Hope this has helped a little. Bon Voyage.