Breakfast - real milk for the coffee, including non-fat. Something besides pastries or donuts. Yogurt, homemade breakfast casseroles. MINI muffins or cut the muffins into 1/4's.
Lunch/Dinner -- homemade hot dishes, most coaches work 5 or 6 nights a week year-round so getting hot homemade dinner food at a meet is really nice. One of my favorites is mexican style crockpot chicken served with tortillas or chips and fixings. Chili, stews, italian baked dishes, BBQ.
It's nice to leave something out during the sessions too b/c if one runs late and then next is starting or there are multiple competition floors at the same time we just have to grab when we can. The worst is when the food is only out for a short time, or it's catered and arrives late and then next session is already started, etc. Also personally not a big fan of lunch meat sandwiches, esp. if they are pre-made on white rolls.
Water or bottled juice for the non-soda drinkers.