You can't go to Amsterdam and not go to the Red Light District. It is in the middle of the city right off of Dam Sq and 5 minutes away from the Main Rail Station. It is great people watching and interesting because for some reason it isn't sleazy. Not really, I mean it is full of tourists gawking...more
I am a flower lover so no visit to Amsterdam is complete if I can't see tulips or whatever else is in season. There is a reason that Amsterdam hosts some of the largest horticulture shows in the world.
This city is full of amazing art. There is no better museum than this one. I have been there many times and it never gets old and stale. Not huge like the Lourve, I would nevertheless hire a guide to show you the highlights.