Hi Terr0rX,
If I were you I would book hotels for every city in advance because you´re going in the high season. Especially when you are going with a big group, you might have trouble to find rooms if you don´t reserve a room.
Another thing, are you sure you want to see all these cities in just ten days?
taking travel time in account you´ll only have just one day for every city, especially for Rome, Berlin and Amsterdam you will need more time if you really want to get the feel of the city.
My suggestion is to skip some cities so that you have more time for the others. For example I would drop one city in Italy and one in Germany.
If you decided to go to Amsterdam I have some tips for you what you have to see and to do, because I´m from Holland and I have been to Amsterdam a lot.
You can go to the Anne-Frank museum, it´s not very big but it is very impressive. In case you don´t know her, she was a Jewish girl who was hiding for the Germans during the war in the same house the museum is. She got famous for the dairy she wrote in this time.
In Amsterdam you have a lot of squares you can visit for a drink, like Leidseplein and Rembrandtplein. A real Dutch folk neighborhood is the Jordaan, it´s definitely worth to visit.
If it´s sunny you could have a pick nick in the Vondelpark, like the locals do.
If you have any more questions, just ask!
OHannemarie
[ Edit: Edited on 25-Jun-2009, at 01:10 by OHannemari ]