Pencil skirts = classy and classic, not slutty.
If a woman looks slutty in a pencil skirt, then she's probably buying the wrong size. Some women look trashy because the skirt is too tight across the butt. Curvier women need to buy the size up that fits their behind and then have it tailored to fit in the waist. (I know this from experience - I'm neither tall nor a size 2)
ETA: Forgot my suit recommendation. I agree with Ann Taylor, but ultimately, you should just spend a few hours at the mall and try them on (as I'm sure you know). While Ann Taylor suit fits me extremely well (except for hemming), J. Crew just doesn't work for me. And I've heard the *exact* opposite from one of my friends.