Until last year the 757 was the only way to get a direct flight from Phoenix to Hawaii. USAir then AA flew the 757 from Phoenix to Kona, to Honolulu and also the Maui. Hawaiian flew it only to Honolulu.
Last year HA replaced the 757 with the A330 -- which made for a MUCH nicer business class experience.
This year AA finally got around to switching to the A321 Neo -- newer interiors and electronics of course -- not clear that the flying experience was much nicer.