HNL to KOA is very cheap-- so best to pay under $100 than burning an extra 5K miles. it is a short flight-- definitely 767 on the dfw/hnl vs the 737/757 DFW/LAX and then 757 lax/koa- aside from HA, there is another company called GO.
www.iflygo.com The prices are competitive- HA offers similar prices, but GO may charge an extra $17 for a checked bag.