Sorry, I'm coming in even later. I'd suggest we follow the Auckland Urban Area as defined in Statistics NZ's 2002 Regional Summary publication (at least until their approach for the 2006 Census becomes clear). This area is divided into four zones: Northern, Western, Central and Southern Auckland. (Profiles of the zones, including links to maps, are listed here.) The Auckland Urban Area includes the Hibiscus Coast, Kumeu, Ardmore, Papakura and Drury, so it encompasses Papakura as well as the four main city councils, and stretches beyond into the Rodney and Franklin districts. It does not include Pukekohe, Waiuku, Waiheke, Helensville or Warkworth (which are the other urban areas within the Auckland region) or Muriwai (which is classified as a rural centre).