"Dress like the job you want to have, not like the job you're applying for."

Very nice. Put into words my vaguely-formed concept of why I won't be pulling out the suit for future interviews.

For interviews, the best advice I've heard is to remember that you're evaluating them as much as they are you. If they demand/care that you dress a certain way, perhaps it's a good sign you don't want to work there (unless you're into that kind of thing).

I have read posts that hint at a bit of hypocrisy in startups, though: "We wear t-shirts because clothes don't matter, but if you wear a suit you're unfit for startup hacker life." Bear that in mind if you really LOVE wearing suits. :P