Courtenay Place!

And yeah I misplaced all the consonants with Wtg ... should have been Wgtn

Agree about the Uber.    If you had a bit more time the Valley Flyer would be ideal.    It goes through the bus only tunnel, up Courtenay Place, Manners Street, Willis Street, Lambton Quay, Railway Stn. area.   

Better off getting a cab into Miramar and going to lunch at one of the cafe's there, and maybe doing the Weta Cave tour.  Getting in and out of the city and also having enough time to do anything could be tight.

DjShadow:

 

There is Bus #91 - Airport Flyer that will take you into the CBD or even out to Lower Hutt if you wanted

 

https://www.metlink.org.nz/timetables/bus/91/outbound

 

I use this most weeks.  It's about $8 each way and faster than a car during peak times.  It's an express service and buses have their own tunnel, plus some bus lanes. 

Courtney Place is the third stop (usually about 15 minutes from the aiport).  There are 10 stops in the CBD and the bus has audio announcement of the next stop.  It's a handy service.