What to wear to a Job Interview?

These past couple of days I've had job interviews lined up, hence why I haven't posted any outfit pictures, but then I thought to myself maybe I should post what I wear so I can get some tips!  Maybe what I wear is not professional enough, or not satisfactory, so I thought I would share what I wore the past two days to see if any of you could help me out, and maybe those of you who are in a similar predicament as me could indulge in the same advice.

On Thursday I went to a "business" office and I actually had my hair up but I took these pictures at night time afterward so excuse the strange atmosphere and lack of feeling (I was sleepy and really really full from dinner on Friday).
Old Navy gray trousers, white shirt, Theory blazer, cream kitten heels

Friday I went to an interview at a bank and I left my hair down (didn't care) which turned out to be a good idea because the office environment (not the counter, but the corporate building) was business casual.

So what do you think? What do/did you wear for your job interview?