Alot depends on what type of department you are interviewing with and what type of background your superior has. FWIW, I have always worn a suit. A tie is not a prerequisite, but certainly show a level of professionalism when meeting your future boss for the first time. Fisher was correct with his reference to your personality. Technical knowledge comes well after your ability to socially interact over a long trip Good luck and let us know how it goes-
B