We have the hotel booked already, for next July, but not the plane tickets or activities. We'll mostly stay on Oahu, but plan to spend a day on Big Hawaii to visit the Volcano National Park, and we really want to visit Maui. Interesting twist: we're taking along FH's brother and his girlfriend, a couple we always have fun with. We figure they can do their own thing half the time and we won't get bored with each other. But besides that, any advice for places to go, to avoid, experiences you had, etc?