Originally Posted by dshreter
Totally agree with Fuuma, I feel like I must be taking crazy pills here reading some of the advice.
West Coast business attire = button down and slacks
West Coast IT = polo shirt on a good day
I realize this is an interview, but to wear a suit, or even a sport coat I believe is to disregard their culture. In an interview they are assessing two things: if you'll be competent and hard working, and of almost equal importance is if you'll fit in with your peers.
They specifically stated business casual, so regardless of the statement you're trying to make by dressing nicer, the first thing that comes to mind is you can't follow directions.
I would wear a conservative button down with slacks, no tie. Depending on the firm culture, if more artsy or something I'd wear a patterned shirt (stripes or check, something boring) with a tie in that case.
Agree with both Fuuma and dshreter, and will point out that finding pics of your (hopefully) future colleagues online is exactly what you needed to do. I always recommend for people to find out how they dress however possible (a secretary, HR, Facebook, company website).
There is no way you should wear a tie. If you're under 30 or 35 (and you sound like you are), you shouldn't be wearing a suit without the tie, either, IMHO. That's casual for the older crowd, but still way overdressed for 20-something IT on the west coast.
Wear a nice button-up and some slacks, possibly even a pair of better chinos. Nicer brown shoes, and DONE. You'll be better dressed than everyone there but the VP of marketing, and you'll show them that you can clean up, but that you still fit in. For your first day of work, wear jeans and the appropriate TshirtHell shirt with rude saying (kidding).
FWIW, when I went to my interview like this (young, west coast IT), I wore jeans and a button-up with some nice brown shoes. I was in a roomful of people wearing suits, and the HR woman came in with no shoes and a leotard top on. It wasn't my dress that got me in, but I have no doubt it helped me a lot that I was completely comfortable in what I was wearing while being interviewed by people wearing athletic shorts, sweatshirts, etc. My 2 cents as a NOOB.