You guys have it down! I loathe packing lunches, but this past year we started using the same Thermos trick for my kids' lunches. We eat pretty healthy too, and my kids would rather take chicken, homemade mac & cheese, soup, or something like that than have cold lunches. The "soup" Thermos containers are awesome for things like this. We would pre-heat them by filling with hot water for a few minutes so the food would stay hot longer. The kids said they could tell the difference when we did this and when we didn't.
For in the parks though, we've always had to have a stroller. So I would take snacks & cold bottled water in a collapsible lunch cooler in our backpack and just leave it in the stroller. With younger kids who think they're going to wither away and DIE if they don't eat every 2 hours, it was just easier to have things at the ready. My husband would much prefer to not pack and haul lunches, so we typically eat breakfast in our room and splurge on park/resort meals for lunch and dinner. We have bottled water, fruit, and snacks in our room for the in-between times. But we have never spent the "average" amount - perhaps because my kids sometimes share a meal, and I'll sometimes order off the kids menu as well. There's no need to kill ourselves with food... we'd much rather spend our time touring than eating!