not sure how exactly it works for sociology, as i am in a foreign languages phd, but some things i wish i had looked into: courses recently offered (a lot of departments list courses from YEARS ago, which may give a false impression); current research interests/productivity of faculty (again, they may list expertise in a field and then you find out they have moved on to a different trend, leaving you isolated); general lifestyle considerations (where would you like to be geographically, what are the people at that university like-- in that sense it can be good to email current grad students); hiring records of the department if at all possible to obtain; does the department in question have active links to other departments/institutions that would be meaningful for you (i, for example, wish i had known that my institution did not, at that time, offer a certificate in feminist theory). these are some general considerations i wish i had looked into. a campus visit can be invaluable in getting a sense for the vibe and atmosphere, as well as the diversity of the department.