We are looking at a couple of places on Oahu that get good reviews on Trip Advisor. One is the Hawaii Firemen's Surf School (which I think Aulani uses) and the other is the North Shore Surf Girls. If you book on your own and just drive yourself you'll save some money over what you'd pay through Aulani as you know they're going to try to make a few bucks on you. We will likely use the North Shore Surf Girls because we can book the 3 of us as a family for sort of a semi-private lesson. They are currently ranked #1 on the North Shore. Plus we want to spend a day on the North Shore anyway.
I called Hawaii Fire Surf School directly and booked a lesson for my DD9 with a pick up at Aulani (I went as a ride along) for our trip this past Oct. It worked great and DD LOVED the lesson.