Boma does have a very good buffet. Our favorite is 1900 Park Fare at GF. We've always had good food there and my DH enjoys getting an omelet made to order. The buffet is fruit, eggs, cheese blintzes, waffles, bacon, sausage, gravy, pastries and strawberry soup.
At Epcot, we have grabbed a breakfast pastry at the Fountainview Bakery. This pastry has egg, cheese and sausage or bacon in it. If you get there early, this is a great place to grab a quick breakfast. We've also had a breakfast plate at the electric umbrella. Nothing special, but you do get little tater tots, scrambled eggs, bacon and a biscuit. Nothing to write home about, but it does fill your stomach and is a quick meal.