Nature's Path Optimum Zen cereal as a base (already a nice mix with a subtle ginger zing)
Mixed nuts
Peanuts
Lots of M&Ms
Pine nuts
Craisens

I mix it all up in a great big tupperware cereal container that stays at home: 1 or 2 loads are good for a full season of hiking.

For each trip I fill up a Nalgene wide mouth bottle (500ml or 1000ml depending on # of days and people). I know the Nalgene is heavier than a zip lock bag but it is entirely water and rodent proof with no fear of failure. If you have a pack with dedicated bottle holster, you always have a snack ready to hand.