回复：我曾经问过公司一个面试过我的老者

- i did wear suit the very 1st time fresh out of school. employer paid flight/hotel/rental-car. it's kind of formal
- it depends on what kind of business you are into.
for engineering, if local, probably ok not wera suit
- i never wear suit later when switching job since all are local. both sides are casual.

AGAIN, as you mentioned, little more formal helps (never hurts).