I've worn a black suit to almost all of my interviews, except for Wisconsin which was informal...got to wear a nice shirt and slacks...no tie...woohoo!
As long as you look respectable it doesn't matter, blue or black, or gray or brown, or whatever. I seriously doubt it'll make much of a difference. You can wear the greatest looking suit on earth, but if you act like a dumba$$ in the interviews then you still won't get in.
Good luck,
Adam