I always try to get an 'Ohana dinner in. Its one of our "must do's". If your kids aren't picky, they'll love it. The chicken and steak are excellent, and so is the shrimp if your kids are into it. They also do a thing every hour or so where they have the kids that want to go around the restaurant pushing a coconut around. Now that my kids are past that age, I find it somewhat annoying, but it doesn't usually go on too long.
The main thing you need to remember is that 'Ohana is a tough reservation. I'd encourage you to book it as soon as you can. On my recent trip, I was unable to get anything except 9:30PM for a long time, but a 6:30 popped up closer to the date. It is a reservation that requires a credit card to hold, so there are cancellations.