Use an airline credit card to get your first bag free
Alaskan, Hawaiian, American, Delta, and many other airlines that fly to Hawaii offer credit cards with 1) free miles for signing up and 2) one free checked bag when you book your ticket using the card. They also usually waive the annual fee for the first year. So if you don’t already have an airline credit card, now’s the time to sign up and use those bonuses toward your flight to Hawaii.
(Or, if airline credit cards aren’t your style, fly Southwest, which always offers two free bags!)
By the way, you can check more than two bags, but it gets pricey quickly. On American, your third bag is $150 and your fourth is $200. On Alaskan, your third and every additional bag beyond is $100. Southwest charges $75 for every additional bag beyond your two free ones. In other words, choose carefully!