I live on the Big Island in Hawaii. Alaska Airlines now flies into KOA and they use a Boeing 757, but I don’t see this particular airplane listed w/ Alaska Airlines. Can you update so I may view seating.
To our best knowledge, Alaska Airlines does not fly any Boeing 757 aircraft, however, there is an AA code-share that flies KOA-LAX. This flight is operated by an American Airlines Boeing 757-200, with AA flight number 246, and code-shared as AS 1846.
Alaska Airlines does not fly the Boeing 757. They operate a Boeing 737 fleet only. The biggest being the 737-900 and the smallest (with the most range. More likely to be on a Trans-Continental flight) the Boeing 737-700.