I've had oral histories on the brain because my US history students just had to do one (on the Cuban Missile Crisis in case you were wondering). My "scientific" process for which president to talk about today was that I saw Jimmy Carter's White House Diaries at our library while chasing my two year old around after story hour. Anyway, the Carter Library has undertaken extensive oral history interviews and some of their exit interviews are available online, as PDFs. You can, of course, listen to them all at the Carter Library in Georgia. The interviews used this set of base questions for these interviews:
What positions have you held in the White House?
Did you have any previous job experience that helped prepare you for your White House duties?
What were your duties in this Administration, and to whom did you report?
Describe a typical day in your White House position.
How was your office organized? Superiors/Subordinates?
What have been your most significant assignments and projects? Which gave you the most personal satisfaction? Are these assignments and projects well documented by your official files?
What do you believe was your greatest contribution to this Administration?
Were there any assignments or projects that you would handle differently now?
Were there other White House Staff units that worked closely with your office in carrying out your responsibilities?
As you leave the White House, what new insights have you gained concerning the governmental process?
When did you first meet Jimmy Carter?
By whom were you hired to work in the Carter Administration?
Were you involved in the Presidential campaign of 1976? If so, what were your duties and to whom did you report?
What disposition has been arranged for the official files that you created as a member of the White House Staff? What types of personal files have you maintained?