Any airline worth a front end passenger nowadays should have fully lie flat (that is horizontal not sloped) seats in business class for long haul flights. Sadly few do. The website Flat Seats has more information for the travelling connoisseur, with information about the long haul business and first class seating of virtually all airlines. Some airlines have angled or sloping lie flat seats, you lie flat but slide to the ground, others are still back in the 1990s with recliner seats which is acceptable for flights of four to five hours max, but not if you are expected to sleep properly.
So, what's the situation for flying in and out of New Zealand? I have looked at the airlines that serve New Zealand (and Australia for flying to Europe, since you can often fly across the ditch and get a good deal), to see who has what sort of seats in business class (not first class, I'm not that rich yet!). Airlines not listed either have no business class or only fly on short routes to and from NZ.
FULLY LIE FLAT SEATS
Air New Zealand (747s and 777s only)
British Airways (connecting from Sydney)
Virgin Atlantic (connecting from Sydney)
ANGLED LIE FLAT SEATS
Cathay Pacific (installing fully lie flat in 2008)
Qantas (747s and Airbus A330s)
Singapore Airlines (fully lie flat on 777-300ERs only)
CRADLE RECLINER SEATS
Air New Zealand (767s and Airbus A320)
Air Tahiti Nui
LAN Chile (angled lie flat being fitted)