Commuter with occasional longer rides: SPD
Bike (geared or fixed) that you use only for riding (not walking or riding to a destination where you will be walking around a lot): road cleats. Look, Speedplay, etc.
A lot of the fixie dudes I roll with really like Time Attack style cleats as well. Bonus: they rock for CX, too.
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Attack in the feeling because it says I'll win absolutely.