We stayed at the Hilton Waikoloa on Hawaii when Sarah was 4. It was a big resort and the food is outrageously expensive. I think we only ate one meal there, the night we arrived and that was it. Also, they didn't have a lot of kid friendly meal options for dinner, or at least none that were OK by my picky eater LOL! So we ate off property almost every meal except breakfast. (DH was Hilton Diamond at the time so we got a free breakfast on the Hilton Honors floor. It was light, but it tided us over to lunch.)
We ate in Kona several nights and also at the King's Shops a couple times.
We bought a ton of food and beverages at the Costco outside Kona. I would really recommend that. We were not the only people hauling around our own drinks and snacks in a cooler. It was super handy for beach days. We went to several beaches up and down the Kohala coast. I think Sarah's fav was one just slightly south of Kona where you could walk right up to sea turtles. It was so cool.
We did drive over the volcano side. We made a day of it and made several stops around the island. We did not hike out to the caldera, because that would have been too far for Sarah. But I would have liked to have spent more time there. I wish in retrosect we had spent one night near the volcano (perhaps in Hilo) and spent a whole day at the volcano. Even without hiking out to the eruption there was plenty to see and do to fill a whole day, even with a 4 year old.
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)