Whenever I have foreign friends visiting me, I take them to Kinderdijk. If you want to see windmills, this is the place to be! You can have a nice stoll along the windmills and in high season you can also visit some of the windmills and you can make a boat trip, which can be nice on a hot day. You might be unlucky and run into a tourbus of Japanese tourists, but generally this is actually not such a touristy place (when I go on Sunday mornings there's hardly anybody there)