My advice:

1. Don't wear really light brown shoes, especially with a navy suit. Everyone is doing it and it looks like s**t.
2. Wear a subtle tie with a white shirt. (Subtle tie = foulard, solid-color knit, challis, etc. NOT repp or Hermes.)
3a. Wear a suit, preferably two-piece.
3b. Wear a suit that fits. Don't bulge.
4. Don't wear a hat, or a tie clip. Hopefully you do not have to be told this.
5. Don't look like anyone in GQ (see 3b).

Despite no one else knowing how to dress well anymore, people still can tell (mostly) when *you* are dressing well. So an OCBD (a good quality white one), higher rise, darker shoe... None are "in" at the moment with the spread-collar, shiny tie, skinny suit people, but you're still going to look professional and good to them...

But ultimately, you're there to sell yourself, not your dress sense. Save the uni stripes and repp ties for when you have the job... At an interview, you don't want them to remember what you were wearing, you want them to remember YOU ("mhalat, he was the Guy Who Said Smart Things," vs. "mhalat, was that the Guy With The Weird Outfit?"). I'd go for navy suit, subdued tie, black or cordovan shoes, white shirt (point collar or button-down).

I'd PM Coolidge, too, depending on when your interview is (I don't know if he ever looks over here on the Wardrobe). I'm sure he'd have good advice for you. Also - aboot, sorey, Canada eh, etc. etc.