With most of the athletes living in/between Amsterdam and Castricum, we use facilities in Noord Holland with the key workouts on the track at Zaanland Athletics Club. The Zaandam location has a new 6 lane Polytan track, with a grass and gravel loop around the track. It has small weight room and track shed with all you need, and a big chain fitness center around the corner.
Zaanland Athletics Club (map) is easily accessible by car from the A8 and A7 highways. Schiphol Airport as well as Amsterdam City Center are less than 15 minutes away. Public train transport will get you to Zaandam Central or Koogerveld train station, 5 minute warm up run from the track. Or take the bus to the stop next to the track.
Next stop from the train station is Castricum, where you can hit the unlimited forest trails of Noord Hollands Duinreservaat around Heemskerk/Castricum. (Peter lives here).