City directory work can be tedious.
If you are stuck on a family (and even if you are not), tracking them through every extant city directory could answer some of those nagging genealogical questions. Entries could reference deceased spouses, contain an employment reference of which you were unaware, document a short term move across town, or provide other details about your urban relative.
Don’t forget to look in the “back” of the directory for reverse directories (people listed by address), business directories, church directories, and whatever other gems an editor decided to include.
Occasionally cities have multiple directories for the same year printed by different publishers. Make certain you’ve seen each one.