When I think CIA I think of When I think of FBI I think of Give me the gun and let me shoot something.
I know it is not quite this cookie cutter, but... You want to mess with foreign type stuff or domestic type stuff? Covert investigations or Overt investigations? There is a chance with CIA you wouldn't be able to tell anyone you worked for them. Usually not the case with FBI... Know a foreign language, especially Korean, Arabic, Chinese? High demand at CIA.
this guy who worked for the CIA spoke to my school, was a pretty cool dude and he plain and simply told us that they have many spies all around the world living a double life.