Amsterdam is overrated unless you are going with a bigger group to party. My wife and I went and we had a good time but it's such a party town it'd be much better with friends.
If you do go, make sure you rent bikes and ride them around for a day. It's a life changing experience. We rented them and rode north out of town zig-zagging through the suburbs to Zaanse Schans to see all the old windmills. The ride is so easy since there's literally no hills there. All the locals ride one speed bikes with no gears. It's quite the sight to see a 100lb woman riding her bike with another 100lb woman drapped across the back. Dogs too!
Also, if you go to Amsterdam be sure to go to
http://wynand-fockink.nl/ . It's an old liquer distillary that's served the Dutch Royal Family for hundreds of years. They have an incredible selection of fruit brandy. The tradition is to bend over and take your first sip out of the class without using your hands so you don't spill when you pick it up.