We are tea drinkers so, we bring an electric tea pot if we are staying in a hotel type room. Then, I bring cereal with milk, instant oatmeal, use the night before's dessert for breakfast (especially if you are too full to eat it), Fiber one bars, etc...
My friend gave us a great tip on the refill mugs-----she brings a bag w/her and puts the mugs in it when finished; she then drops it off at luggage service at the hotel-they pick it up at the end of the day and just walk in the food court ready to go. Most of the food courts have an area to rinse out the mugs. I thought this was a great tip---no more lugging the mugs around all day or sending DH running back to the room to drop them off.