When I interviewed for residency one of the attendings (who would go on to train me) was so overcome that someone was in 'something other than all black' that it sparked a whole conversation and made for a great interview! It depends of course on what you're interviewing for but if you're either established enough to be less conservative or in a place/city that is less conservative play with colors and sheath dresses! This is also a great look for conferences and podium talks -- professional but not stuffy and boring! Remember that you may take the jacket off for meals so keep the sheath simple (both of these are from Black Halo) and make sure you can wear your shoes all day. I prefer an almond-toed pump to a pointy-heel for this. Playing with a little color is a good way to let your personality peek through (just a peek in an interview is more than enough)!