Some of my favourite cereals are shredded wheat, cheerios, rice krispies. All very simple cereals. If you're feeling fancy you can have a porridge with jam or a granola with no fruits.
The only thing to say is the milk. I know a lot of people develop lactose interances as an adult so it might be troublesome to keep having such a high lactose intake. I think some milk alternatives are much nicer nowadays and add some of their own sweetness to cereal if you like that. I personally have no issues with my low fat dairy milk every morning