We have been going to Ohana for years, and one of our three boys is a very picky eater! They have childrens' items at no extra charge (meaning you pay the $14.99 and children can eat the regular menu items or order kids' items, too.) In the past, they offered the kids' items automatically, but when we were there earlier this month, we had to ask. We got mac and cheese and chicken fingers with fries, I think, but they had many other items for kids.
I have never been to Kona, and we have always loved Ohana. So it's tough for me to say anything negative about Ohana - the salad, bread, potstickers, wings and dessert are outstanding. That's enough for me! But the meats have not been so good lately. While we love the appetizers and desserts, the $30 per adult (and we have pre-teens who qualify as "Disney adults") is quite a bit. Our youngest (a pre-schooler) LOVES the coconut races, limbo, etc., but our older boys are not into that anymore. So we have been considering Kona as an alternative - looks like they have the potstickers and wings!
But OP, at ages 3 and 5, it was great fun! So if you haven't been, this might be a good time to try it.