[whpalmer4]

Oops, good catch, Dennis! I read the question as wanting a way to change only OmniFocus, but perhaps that was too narrow a reading. One can certainly get the longer date variants by changing the short date format. The request for special treatment of nearby dates does not seem to be amenable to solving that way, however.

If you do change your short date format (in the International preferences), it appears you'll have to restart OmniFocus before you see any change.