Time up there was pretty short , but managed to cram in MOTAT , Ardmore , the big museum on the hill ... thank goodness for a GPS in the rental.
Its been while since i navigated the Auckland motorway system .. a tad daunting if your not used to it , however , except for one exit overshoot , i did well.
I have to say , the drivers up there are a lot more tolerant than down here . If you indicate a lane change (even at the last minute) they let you move.
I used "About NZ rentals " , older cars , but everything I needed , plus free pick up and drop off at the end . Stayed at the airport Ibis ... again basic but clean and well priced.
Spent a little time with the spotter brothers (nephews) , but mostly with my brother . For me , Ardmore was the highlight and spent most of the day there yesterday watching a couple of Harvard's doing circuits with all the other GA stuff.
The warbirds visitor centre is well worth a look. ... really nice people and a great atmosphere and an amazing library upstairs.
Weather was perfect , all in all a great but short break.
The lads got ... hundreds of photos , some of which I'll share during the week. I only took a couple which I'll post when I get time.
The only downside was waiting to board for the flight home . As I left the security area I noticed people sitting on the floor in the corridor that leads to 2 of the gates.
As I got closer the crowd got bigger ..... I estimated 300 plus people in an area designed for 100 . It was hot , it smelt like a portaloo ... not good at all .
Finally got to board only to find a guy in my seat ... 13A ... more leg room and a window , a small one , but a window.
With the assistance of one of the cabin crew (delightful young lady ) we got him moved to the next seat ..where for the next hour or so he sniffed , spat into a paper cup , sneezed onto his phone screen and wiped it on the seat in front , while the smell of his 2 bags of Chinese takeaways in the overhead locker drifted through the cabin and into my carry on ... charming

But , i suppose ... you pay the price , and it was cheap ...so you take your chances .

Pleased ya got the window seat .. some reason they took out the window whined down handles .. ya no .. old school Mirror Minor sorta thingys ... MOTAT , almost a Ferrymead , like you pointed out we need a NZ aviation Museum , again Wigram would become the ideal spot , it has the room but also has the history to go with . 
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I made it on, in one trip Wellington to Auckland parked in five and a half hours.
.. then as the flight continues they get to understand exactly why ya require that window seat .. course the best example was the German tourists , and da course the return flight from NZFF meeting at Tauranga , the lady really went .... like throw the paper out .. I think this is were you promote yourself , but also to make it interesting to someone who simply ya not going to meet again.