What else is there to do?
Should you wish to stay longer than the 3 convention days, there is a lot more to see and do in the Netherlands and surrounding countries than just Amsterdam. For example, the world's most beautiful bookstore is located in Maastricht, The Netherlands. It was voted Most Beautiful by The Guardian, a leading English paper, and its name is Selexyz Dominicanen. It's a 2 and a half hour train ride from Amsterdam.
Other examples of things you can see and do include the Keukenhof and its world famous flowering bulb gardens, Madurodam which will show you the whole of the Netherlands within a short walk's distance, and de Efteling, a themed amusement park where fairy tales come to life.
For mills, clogs and old fashioned houses, visit De Zaanse Schans.
And for even more ideas in Amsterdam, see I amsterdam