Air New Zealand was the best ever to travel with boards but now they are after the $$$ - which sux as they market NZ as a board sports heaven (which it is) and AIRNZ is generally a very good airliine to fly with.
International - extra bag with surfboard $100nz each way.
Hawaiian - $24/ $40 each way inter island + when u buy a ticket it is not clear that u did not pay for your first bag. They ripped me - sold me a 1st class ticket that included extra bags and chrged me for 2 extra bags too - $200 one way maui to oahu! and to top it off they absolutely smashed my sup - dragged it along the ground on the rails and crushed it in parts.
My advice - print out from the airline website the baggage deals - then u don't get into that utterly shit situation before u leave.
U gotta be careful labeling your bag contents with what is not inside - they don't like it for security reasons... so they say.... seems a bit stupid tho, don't believe anything to start with would be best way to go....