I usually figure about $100 per day for our family of 4. Our two kids are too old for children's meals. We bring a cooler and fix sandwiches on a couple of days and eat them at our hotel room. During a 7-10 day stay, we manage to sample all types of dining opportunities including fixing our own sandwiches for lunch or dinner, eating breakfast in our room as you mentioned, counter service and food courts, character breakfast and/or dinner, sit down lunches, and more rarely a sit down dinner. Another advantage to eating breakfast in the room other than just saving money is that your family can "multi-task"; while some are using the sink area, showering, etc. others can be eating and then switch around.