At the Polynesian resort, we suggest Captain Cook's Casual Eatery. It's now open 24 hours and features plenty of quick fixings and a full grill until 11pm. Prices are very reasonable. We found this a good choice for a quick bite in the morning as they feature cereal, bagels, muffins, juice and coffee. Just enough to get us started on our day.
Most resorts feature a similar fast food option.