I am perhaps in the minority here, but here goes...
We are 2 adults traveling in May with our almost 20 year old son, who is also a full meal eater over sweets and treats, especially since recently developing an interest in weight training, etc. We go on vacation to enjoy an escape from the real world, and that includes getting away from meal prep, groceries, cleaning up after meals, etc. as much as possible. We will have a generous food budget (probably around 300/day for 3 of us, but I don't think we will hit that every day) and will look for ways to enjoy the food, eat some relatively healthy stuff so we feel well enough to keep up, and keep my son satisfied. This may include one sit down meal per day where my husband and I might get apps and share an entree (for budget and calorie concerns) while my son gets his steak, and also includes looking for counter service menus with more satisfying options than just fried foods.
Breakfast is an opportunity for supplementing in the room with whole fruit and peanut butter, protein bars/trail mix--these are all things my son loves, so that is easy--won't work if your sons don't enjoy! That will hold him over until we maybe grab him a breakfast sandwich at Starbucks or something mid-morning--he will want to eat frequently. My husband and I could get coffee and split a sandwich, knowing we will splurge on a meal later.
We are sometimes planning our sit down meal at brunch or lunch, which can be a more affordable option. So my son will feast on a protein filled $20 entree at 1pm, and then maybe an afternoon snack or treat (ice cream), and then a decent counter service dinner.
My point is, for us, we will have minimal food in the room. It will focus on easy, non messy, healthy food for energy. We will choose restaurants, including quick service meals, wisely based largely on our son's preferences, and we will splurge on things we love, like special ice cream sundaes, etc. When we eat sit down meals, we will choose the more "reasonably" priced ones (grand floridian cafe, for example, over signature).
My experience is that no one really wants to eat meals in the room. No one wants the usual snacks and things we can have at home. If something is special and we want to splurge, we will. Having a few basics like whole fruit and protein bars is definitely good for when someone is starving, which is rare. or to just hold over until the mid-morning food stop. You will have access to the quick service at Poly and GF, both which have healthy, reasonably priced options. You can even grab a kids meal for an extra meal boost for the boys (like a side dish for their meals), which we might do, as it comes with fruit, milk, etc.
This is just my experience, and not at all a criticism of those that like to load up the room, eat on a tighter budget, etc. Just for us, this trip comes rarely, and we really enjoy the escape from reality. So, we splurge, but we splurge in a controlled fashion.
I can see this being an example of our day...
$25 quick service at hotel for coffee, quick breakfast foods
$25 mid morning snack at starbucks or similar for 3
1:30pm Grand Floridian cafe brunch/lunch, 3 entrees, tip $80
4:30pm ice cream for 3 $25 (my husband and I could easily share)
8:00 counter service like ABC commissary $50
That is $205 and a pretty full day of eating.
People are right not to waste money on bottled water, or even soda, etc. That is a budget killer.
Good luck whatever you decide, and I hope it works great for you and your sons. Enjoy!!