I've only been to Amsterdam once, for one night. But if you find yourselves at a loss for what to do one evening, do somehthing very simple: go for a walk.

Amsterdam is wonderful to wander around in the evening and when you walk through residential districts, it's intreguing to see all these houses and apartments with the curtains wide open and lights on, with the occupants living their lives in full view (it's no surprise Big Brother was a Dutch invention).