We are planning a visit to see friends in Mainz (outside Frankfurt) and Berlin in August, and adding Prague and Amsterdam to our almost 3 week trip. Our Mainz friends have recommended Prague to us and we can only get return frequent flyer seats back from Amsterdam. There are cheap EasyJet seats from Prague to Amsterdam so we are OK with that. We have visited our Mainz friends before and may go with them to Strausburg on the border in France while we are there. What we are trying to figure out (so we can book those cheap EasyJet seats and cheap advance purchase train tickets from Berlin to Prague) is how much time to allocate to see the sites in Berlin, Prague and Amsterdam. We haven't been to any of these cities before. Can you help us? Also, any suggestions for non-city "musts" to do--we will get tired of cities and museums after a while on this trip. We like birding, nature, etc. Thanks.