Ok, let's see. Providing they aren't changing the menu before you fly, this is what you will get:
DCA-SEA - To begin, a fruit plate and warmed cinnamon scone. Followed by a choice of a western omelette with cheddar and ham, breakfast potatoes and a bell pepper confit OR a southwestern chipotle frittata with breakfast sausage and a bell pepper confit. prior to arrival, warm mixed nuts.
ANC-SEA - southwestern chipotle frittata with fresh fruit on the side.
SEA-IAD - Jalapeno dip with garlic toasted bread rounds after departure. Prior to arrival a warmed cinammon scone and small portion of fresh fruit.
Basically, not a whole lot of variety. The frittata is decent but nothing to write home about. Bring some salsa to spice it up. You can also check to see if they have any of the breakfast sandwiches left in coach if you tire of the frittata. On the whole I think you get a decent amount of food for the length of the flights and probably won't need to bring anything on.