You can never go wrong wearing a suit to an interview. I would recommend a solid navy suit or very toned down pinstripe. I wouldn't wear a thick chalk line type pinstripe, since you don't want to go into the interview looking like Al Capone. I would avoid black or brown suits. A charcoal suit would be appropriate.
I would also recommend a clean, crisp, white shirt, because once again, you can never go wrong with a white shirt. I would keep the tie conservative and avoid "novelty" ties, Jerry Garcia ties or very flashy colors.
I also agree that if you have a nice blue blazer and wear that with a shirt, tie and pair of NICE khakis, you'd be fine.
And please don't go into an interview wearing a pair of beat up shoes.
Yes, there will be sharp dressed men who don't get in, and poorly dressed shlubs who will get in, but it never hurts to make a good first impression.
I would also leave the bling home. No bracelets, cufflinks, etc.
And DEFINITELY don't walk in with a briefcase or anything similar. That would make you look like a definite d-bag.
