Don't look at just the alphabetical names in a city directory. There may be directories of businessmen that could provide more detail about your ancestor who owned a small shop, was a tradesman, etc. Rural directories may list owners of specific types of livestock in special sections and some even list who owned what type of automobiles.
City directories may also have reverse directories in the "back" of the book. The point? Get away from the alphabetical list and you may learn even more about your ancestor.