Thanks for the replies. I am flying from St. Louis and into Christchurch via IAH, AUK). United is only operating the leg from St. Louis to the ANZ hub. ANZ will operate the international leg and the AUK to CHC leg.

If I book through United, it says they will not be able to assign seats until I check in. That seems ridiculous for such expensive tickets, purchased 8 months prior to departure. Anyone have luck calling ANZ to get seats booked on United codeshare?

Will the cancellation policy be different. I cannot find united's cancellation policy for this fare.

I am just concerned that if there is a problem, ANZ will say call United. OTOH, if there is an issue at departure, there is no ANZ desk in St. Louis. I guess with codeshare, it's a free for all.

I don't really care about miles as we rarely fly star alliance. This particular trip, we don't have a lot of options unless we are willing to do 9 hour layovers etc. And we will need to book a codeshare trip regardless (AA and Quantas)

I don't think it's a currency issue as I'm shopping on the ANZ US website.