For providing yourself with the most flexibility, as well as not getting yourself "locked-in" (get it? har har) to the just one option of havingclipless pedals, hybrid pedals are for many cyclists the best way to go.
These pedals are flat on one side, meaning they are functional for just about any style of regular shoe. The other side of the pedal has the mechanism that allows a cyclist wanting to riding clipless to lock in their cleated bike shoe, giving them that much more power and efficiency in their pedal stroke.
I have these type of pedals on my touring bike, which doubles as my commuter with its fenders and panniers. That means I can wear ordinary walk-aroundshoes on my commute and not do the click-clack up and down the halls at work, but them switch to cleated bike shoes when it's time for some long distance touring.