Before interviewing that relative, see if you can determine the names of any near neighbors. Names of those neighbors may generate memories of events you never would have asked about otherwise. Census records that are public (if the person is old enough) are one place to get these names. City directories are another (particularly if they are searchable by address). Telephone directories may also help, particularly for those ancestors who were rural.
Ask about your interviewee’s neighbors. You may get more than you bargained for.