We highly recommend booking a guided tour of the museum. Note these sell out several months in advance, so you will need to be quick!
Rent a boat and cruise around the canals! Bring snacks and a bottle (or two) of wine for an ideal afternoon. Mokumboot has various locations around Amsterdam. Other options include Boaty.
Madurodam is a small city full of beautiful miniatures - the best way to see all of the Netherlands in only a couple of hours! Combine Madurodam with a visit to The Hague.
Visit Zoey's birthplace, also known as the city of cheese, candles and stroopwafels. Gouda is about an hour away from Amsterdam by train. Highlights include visiting the Sint-Janskerk, City Hall and the surrounding cheese market (only on Thursdays) and the Gouda Cheese Experience. For a traditional Dutch meal, try "kroketten" at Café Central.