We were in Amsterdam in October and really loved it. Such a beautiful city with amazing architecture. We'd go back in a minute.
The Vermeers in the Rijksmuseum are glorious and the Van Gogh museum is a must see if you're a fan. They also had a Munch exhibit when we were in town.
I think we were the most impressed by the Anne Frank House though. It's so well done and very little in the annex is behind bars or glass, so you get a very personal sense of the place. Angie's so right, though...the lines are absolute madness. If you book ahead on their website, you can completely bypass the line. Instead, you go straight to an unobtrusive door and ring the bell and they'll let you right in. The house is covered by the Museumkaart, which you can buy when you get to the house.
The nine streets area is very pretty and has great shopping. If you're into lingerie, don't miss the Marlies Dekkers store. The SAs there are lovely and the undies are so unique.
And watch the bicycles. OMG. My nightmares featured the "brrrrriiinng, brrrrinnggg" of bicycle bells for days afterwards. You will get mowed over if you don't keep your eyes (and ears) peeled!