Frankly, it's a struggle. However, it's getting better on Oahu. My wife is from Oahu and we are usually there twice a year. Since we are in Kailua, I have tended to look for craft beer on the windward side. Along with Whole Foods, I have found two liquor stores which have pretty good selection. As far as Honolulu, there are more places serving craft beer, and a few breweries starting/in process of opening. Some of the locals can provide more info. Still, it's a struggle...
Brew'd Craft Pub on Waialae Ave. in Kaimuki or Real Gastropub in Ward Center in Honolulu. Good stuff on tap and excellent food. If you are looking for bottles check out any Tamura's Fine Wine and Spirits location, The Liquor Collection in Ward, Bev Mart on Date Street or Whole foods in Kahala Mall.
I checked Real out. It was great. Food, service, and selection was what I was looking for. Thanks Raw. If you are ever in the pacific NW, I would love to return the favor of recommendation......