I have flown Air New Zealand business class many, many times and find it to be one of the best travel experiences available in the sky. Good seats (even on the 767), nice food, talented f/a's, etc. And, NZ understands long-range travel and gives you the opportunity to rest on the flight. I am always most impressed with their service.
UA business is also very good, have flown it transatlantic but not transpacific; if you are travelling to NZ or Australia, give NZ a try, I think you will be happily surprised.