My family and I (4 people total) will be traveling to New Zealand from Michigan once or twice a year for the foreseeable future.

I suspect it will make sense for us to sign up for a Mileage Plus credit card through United because of this.
I'd also like to be able to redeem UAL miles for travel on Air New Zealand for both domestic travel inside NZ as well as trans-pacific travel back to the US as ANZ offers more options than United in and out of Auckland.

Besides these trips to NZ, I don't except we'll use United except maybe 1 or 2 times a year inside the US with the occasional trip to Europe. So, I won't be chasing status on United/ANZ. Instead, only trying to maximize the points / rewards that come with booking 4-8 tickets to New Zealand a year for us.

Am I correct to go with Mileage Plus and not Air Points for these trips? Is it worth getting the QUEST Credit Card?
Thanks from Michigan!