Flying Aloha out of John Wayne has always been the best deal we've found...this year we flew from San Diego for the same price.
Directs may be limited to Hilo, but the drive from Kona to Hilo isn't too bad though, and is scenic no matter which way you take.
I do believe Aloha may have some flights from ONT as well....
do yourself a favor and avoid flights that need a transfer in Honolulu or Maui, those are often late, alway heard people moaning about that.
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I love the big island..............do not pass the chance to go expore Vocano's National Park, fancinating beyond.