Depending on which hotel (Disney or non Disney), I've used the ice bucket to keep small milk. Or the mini bar...just removing a few of their items.
I like to bring bagels, raisins, fruit, trail mix, cereal bars; along with things others have mentioned. Honestly, I bring too much. We also pack the same types of foods to bring into parks as snacks.
I've also packed a soft sided collabsible cooler in our suitcase; & filled with ice from hotel. We just make it a point to change/add ice each morning. Works great.
We find we don't eat as much at Disney, due to heat & just so much to do. My favorite routine for food is: morning snack at hotel to get us out of there fast. A nice treat in the parks around lunch to keep us out of lunch lines (turkey leg?). Good midday meal somewhere in the park when others are not eating & its hottest, so you get a break.(If its a table service you pick, do it while still lunch prices; since dinner prices are higher & often too much food. Lunch prices are served until 4pm I think.) Then another park treat around 8pm. Honestly, doing that, we've never felt hungry. And if we do, I have plenty of peanuts, crackers, trailmix in my back pack. Also, LOTS of water.
We've even been known to split a meal because we aren't that hungry. LOL -- that wouldn't happen at home though.
Epcot is a bit different. We tend to just snack our way around alot. Fish & chips.

While waiting for Illuminations, I save our spot, & DH goes to get a serving of nachos which we share.
I ALWAYS come home with HUNDREDS of unspent food $ I budgeted. People who travel with us agree, they have not been hungry at all either.