You are welcome! I have 3 teenagers (2 girls, 1 boy) and I know how much they can eat, even after having a big dinner! Whitewater Snacks has prepackaged foods too (everything from bagels, peanut butter, yogurt parfaits, etc). Some people will have a delivery from Vons (which is Safeway where I live, which was bought out by Albertsons!) for grocery items and forgotten items like sunblock. We enjoy staying at the Grand when we can. Each Disney property has it pluses!
Another place we like to have a meal is at Tomorrowland Terrace in Tomorrowland. I think it is renamed as Galactical something or other, but I know it as Tomorrowland Terrace. After doing Magic Morning and riding rides, everyone starts to get hungry, so we will have breakfast there. Hubby will get the breakfast burrito, two of my kids will get the breakfast platter, I order a yogurt parfait, and we get a fruit platter to share and my other child will pick off of everyone's plate. If we order her something for herself, she won't eat it, but she will pick off of everyone's plate! She only does this for breakfast. I know, weird. The fruit at Disneyland is very good. Flo's Diner in California Adventure has the same fruit platter too. When ever there is an option for a fruit platter, we will get it and put it in the center of the table so everyone pick at it!
I didn't see when you are going, but I would suggest getting a case or two of bottled water. That adds up fast in the parks and I am very fortunate to have kids that love drinking water! Have a wonderful time.