I'm very petite, so it's hard to find professional dress in my size. Pants: Banana Republic (petite) Ann Taylor Loft (petite) Tops: Same as above + Tommy Hilfiger (outlet) Kohls New York & Co Gap & Old Navy (sometimes)
I buy my pants/skirts/bottoms from Neiman Marcus, Nordstroms, and Lord&Taylor because the quality is AMAZING. The prices do add up, which sucks but I have some skirts from WAY back in high school that still fit me now. (That's a good 9 years.) My tops are usually from either Nordstroms or Bloomingdales because I'm super lanky and everything from other stores just make me look like I'm drowning in fabric. I usually refresh my wardrobe every 2 seasons so I can save some $$$$.
I always get editor pants from express, and city cut at ny&co. All cardigans, blouses and shirts typically from the Loft. The Loft has great teacher discounts, so does NY&CO. As for shoes, I just wear flats... I don't dare attempt to get through a full day in heels.