We take a rolling hardside cooler as part of our luggage; if you don't have one, you might want to buy a little styrofoam cooler. We prefer to eat breakfast in our room, and we've got a young child, so that influences our choices.
We usually buy paper plates, a roll of paper towels, 2 six-paks of 16 oz. soft drinks in bottles, a half-gallon of 1% milk, a box of juice paks for the little one, some orange juice for the grownups, a box of vanilla wafers, a dozen muffins, granola bars, a bunch of grapes, a few apples and a few bananas. I also usually buy about 1 lb. of smoked deli-sliced ham, as I do better on active days if I have a little protein for breakfast, and that keeps well. I always carry a miscellaneous packet of ziploc bags in my luggage, so putting food in the cooler poses no problem.
I put a large Land's End fabric tote bag in the cooler when it is packed, we bring our food into the hotel inside it, rather than carrying a bunch of grocery bags. The food goes in a drawer while we are there. The tote then gets used as a laundry hamper.
