Only stayed there on business but for things to do the kids would enjoy the trams and the zoo and a boat ride on the canals or even the ferry across to Sixhaven. For football lovers there are daily tours of the Ajax stadium (not done this myself but was a popular corporate event).
A great place to eat with a Dutch ambience is Haesje Claes (www.haesjeclaes.nl/) - it makes a change from all the expensive Argentinian steak houses that fill the tourist areas. I ate there at least once a month during 2009!