I'm not as though as kiwi guys and i use a full 3/2 in summer. On Saturday it was quite nice and i was just on shorts on the west coast.
My suggestion are:
1) play with the tide. Outgoing tide and onshore wind means more fun
Then the same spot with different tides can be wavy, choppy or flat
2) even with poor forecast on the west coast you can have some fun.
Around Auckland this is a good guide
http://jckitesurfandsup.co.nz/Locations ... SPOTS.html
As you can see here in Tauranga you can even kite with SW. In an amazing flat water spot.
What i found is that in Raglan, that is an amazing spot, you really need to check the tides and you can't really stay all day on the water.
Around Auckland with Sw you can for example do wave in Muriwai, then go till the south head for an amazing flat water spot. Or head shakespear with mid to low for a nice flat water spot.
Distance between East and West it's just 60km.
Another rule is: with wind from west head west or south west for stronger wind.
with wind from East NE head NE (Orewa or northen) for stronger wind.
Have a lot of fun