Koru in SYD is nice. Koru in AKL good. I think there is an older A320 with biz between AKL-SYD still flying (think it is the late flight) -all new ones are all E.
To see Promo's you have to sign up on each country -some rates are available 1 way so multiple countries better. I am on US, NZ, Au.
Never take PE, only biz which I personally do not like as they flip over so you can only recline to a certain degree. Many others prefer over UA.
Don't expect any bennies from NZ but they do have a buy up to biz if that flight is still available. I bid $200 and got the upgrade. For me the money was worth it for the 3 hours.