Cheerios (GM)
Classic Coke, Bread, Penicillin. (compatible with: bananas)

Rice Krispies (K)
Snaps, Crackles and Pops. Wonderful, understated aftermilk. (compatible with: blueberries, strawberries, bananas)
Grape Nuts [Second Opinion]
They may look innocent enough, but watch out. They'll expand inside your stomach, and you will know it when it happens. Also great for adding live fruit (mostly berries).

Corn Flakes
Classic cereal. Always reliable. They do soften quickly, but it's okay. It's okay.

Special K
Similar to corn flakes, except slightly different. They seem to retain their crunch well.