Nick, I just caught the 21-30. My bad.
9 days isn't a whole lot of time to try and explore Europe. The Netherlands alone could take up that much time. I also don't think you are going to see all Amsterdam has to offer in 2 days. Personally, on a one week trip, I'd stay regional. If you are spending 3 days in Amsterdam, then planning on going to London (that'll take you half a day, traveling there, half a day traveling back to Amsterdam for your return flight), that's 4 days off the bat. That only leaves 5 days. That isn't taking jet lag into consideration, either.
So, 5 days. You could spend that in London and call it a wrap.
I would go Amsterdam, Rotterdam, Cologne, Luxembourg, Brussels, Bruge.
Or, maybe head north to Coppenhagen (but this will eat up a lot of travel time).
I'd try to keep it very regional, though, or else you're spending more time traveling rather than interacting.