BlindPilot,

I've travelled to all of those cities as a tourist wihin the past couple of years. Prague is a great choice and any of the other 3 (Vienna,Berlin,Amsterdam) would be a good choice as well. I wouldn't try to do more than one other city in a one-week timespan.

That said, those three cities are very different in terms of feel/atmosphere and things to do. What are your interests? Art, music, beer...? Vienna has lots of musical offerings in addition to the palaces and historical sites. Berlin has plenty of museums and historical sites plus a vibrant nightlife. Amsterdam has the VanGogh museum as well as other must-see things.

If it were me I'd lean toward Berlin or Vienna over Amsterdam as they are in closer proximity to Prague and could be reached by train without a whole day of travel - but that may not be a factor if you are routing through AMS by air. As some have mentioned here, Krakow is also another great option. Very manageable, fairly close to Prague, and still relatively inexpensive compared with the other three places. It's become a very hip destination.