Going to OGG with my wife, baby boy and my parents. We've booked the flight, condo and car.

Seeing that this is going to be my first time in HI, I thought I'd ask whether there are any activities or attractions that we should consider booking in advance? I normally hate to book these things in advance but I'm not sure if there are any must-see events or sights that would be better to reserve before leaving home.

Thanks in advance for any advice!