I just returned from Amsterdam/Haarlem.
Allot about 1 hour for the tour of the Anne Frank House.
I recommend you purchase tickets online in advance for both the Van Gogh and Rijksmuseum. For Van Gogh, we had timed entry tickets for 9 am - we were very glad because the museum gets really packed and it was nice to see his paintings up close without trying to see and read the captions in rooms that are 6-deep.
The Rijskmuseum tickets we bought online as well. As I recall, I think we had to specify a date but there was not a time. We went later in the afternoon after the Van Gogh! A big museum day, but fabulous!
I highly recommend the Hermitage in Amsterdam. The Hermitage in St. Petersburg, Russia, loans paintings from their extensive collection to the Hermitage. When you go, keep in mind that most people do not see these paintings unless they go to Russia to see them so it is a special experience. Tsar Peter the Great and Catherine the Great were huge fans of western painting and have amassed a wonderful collection. I walked in to the Museum and purchased a ticket on the spot. Crowded but not overwhelming.
Also, go to the Dutch Resistance Museum, in Dutch, the Versetzmuseum (I think). Impressive and very well organized. I walked in and bought a ticket, no need for advance purchases.