While there's a plethora of options on Oahu (and really, you'd be hard-pressed to pick a lemon) I'm with @Allan here. Ko'olau is simply stunning. Make sure you bring an extra sleve (or 4) of balls. You're gonna need 'em!
Other tracks to consider:
So I did play Ko'olau and your recommendation to bring extra (sleeves) balls was spot on. Miss the fairway and you might as well reload. Beautiful course with stunning views, definitely a serious and fun test, thanks again.