On O'ahu there are several Costcos, one is on the way from the airport to Waikiki. It has gas too, and an outdoor food place (most are inside) so anyone can buy pizza,etc from there.
Kauai has a Costco but I'm not sure where, haven't been there, only to Big Island and Maui.
Costco does not do trial or 1 day memberships, but they do, like someone mentioned, let you cancel at anytime and get your money back. Personally, I love Costco. They have lots of premade and prepared foods in the "deli" area that are totally worth it while on vacation, plus bottled waters, snacks, sodas, their pizza is $10 and huge!
Enjoy O'ahu, wave to me as you arrive at the airport LOL, I can see the planes land and take off from my house.

Oh and FYI if you were planning on hitting the USS Missouri it is in the shipyards and unable to be seen but you can of course still see the USS Arizona Memorial (free) and the USS Bowfin. (not free)