Thanks for all the suggestions, ladies.
I thought about this extensively last night (because I could not sleep thinking about how much I hate this job--and no, don't worry, I am not typing this from work, hehe).
I think I would like what I wear to reflect my design aesthetic. I am a big fan of minimalism and simplicity and I always make a point to eliminate what is unnecessary. I also like to work with subtle details. Of course this is not always appropriate, but the jobs in which it IS appropriate are always my favorite.
So having said that, I agree with what Shiny said about playing with color and line. Out of all my bottoms, I like my black pencil skirt the most because it has a little flippy pleat in the back (sorry, don't know the technical term for it), and it kicks it up a notch from an average pencil skirt.
Angie, I love the sound of the outfit you put together. I'm not too sure about the graphic T though (or bronze lipstick...I just never feel right in lipstick). I think to achieve what I wrote about above, I'm most interested in the drape, texture, silhouettes, and seaming of different pieces, rather than making a very loud and obvious statement with a graphic T (though if I got the job, I would definitely wear that to work).
Shoes are a potential problem. I used to carry around a pair of Ferragamo pumps I thrifted and change into them once I got to the interview, because they are excruciating to walk in. But now I think it's time to retire them. They are painful even as sitting shoes--my toes are literally on top of each other. I have my gray patent Natural Comfort shoes, but I don't like them with skirts. They look great with pants though (I can only wear them with my plain black slacks though, since my others are hemmed for flats). I might have to pick up a pair of pointy toe sitting flats or something of that nature. I can also wear my NC low wedge shoes with skirts.
I just remembered this morning that Angie, Laura, and I (and maybe Tanya though I think she might have still been in the fitting room) saw a gorgeous jacket at Mango that I absolutely fell in love with. I think it was cream though, which I'm not sure would be a good color with the pieces I already have (I'm inept at combining neutrals, as I mentioned). I had made a note to ask for it for my birthday because it would have been too pricey for me. I might go back and see if it's still there, if it gets the thumbs up. If not, I'll probably go back to Mango anyway because I absolutely adore their attention to small details and I think that kind of design sensibility is exactly what I'm after.
Now I shall go through all the links everyone posted