Have fun! You should visit Amsterdam too sometime. ;) Btw, 4 weeks for 4 countries, isn't that kind of pushing it? You won't have time to get a good look before you leave again! I suppose you're going American tourist style?
I'm only spending 4 days in London because I went there for 3 weeks a few years ago, and we're not staying in Paris very long because we went there for a week too. Those two add up to less than a week and a half I'm pretty sure, leaving the rest for Italy and Germany. Anyways, thanks!
Have fun! Also, there are 2 legolands in Germany, one in Berlin and one in München, I have been in both, only the second one has the roller coasters but in Berlin it's somewhat cool, too.