First of all, you will LOVE Yacht club!! Our fav is beach club and we love the pool and the grounds and the overall ambiance. We always do a grocery order from Garden Grocer. We love to convenience and don't find it too terribly priced. If you order 60 days in advance you get 10% off your order. They've always given us great customer service.
My athletic 6.5 year old lives off Clif Kids organic bars (she particularly loves the iced oatmeal). These little guy are packed full of good things for the day!
On top of that we always eat breakfast in the room. This trip we are doing 'Ohana and 1900PF however! We order organic milk, cereal cups (cheaper option is a box of cereal and grab some bowls and spoons from the QS), bananas, yogurt, case of water, case of snapple or gatorade, oatmeal to go squares, a couple of individual muffins, apple sauce, popcorn, fruit snacks (for in line waiting) foaming handsoap and bubble bath. Sometimes we add a box of smuckers uncrustables as our kids love them and it's a novelty since we don't have them here in Canada. OH! We usually also order a loaf of bread and jam since one of our daughters is hypoglycemic.
Good value for quick service we always find at Columbia Harbour House, Morrco in Epcot (forget the restaurant name), fish & chips in Epcot, ABC commissionary in HS and Flame Tree BBQ at AK. Honorable mention to Wolf Gang Puck and Earl of Sandwich in DTD.
For table service we will ALWAYS do Teppan Edo, in fact normally we do it twice, the prices aren't insane and our kids eat the most here. We love that it's sauteed veggies, chicken and shrimp along with brown rice. They gobble it ALL. Raglan Road in DTD is amazing. We are also probably the minority, but we do love doing CRT for the ambiance as well as avoiding princess lines in the park. Tusker House Breakfast with MIckey is by far the best on property!!! Sad we couldn't secure a ressie this trip.
Also...our kids get bored of water, so we also bring those squeezable water flavors with on our trips. It also makes the water taste better if we refill bottles in the park

It's a cheap alternative to buying juice or soda. Both of which we aren't personally fans of. Also, we like to get a Trenta iced tea from starbucks, passion tea is the best, ask for light ice, and this is a nice alternative and caffeine free. And it's actually VERY cheap. A trenta gives each of our 4 members appox a cup of liquid for under $3.00.