There's a couple of reasons I wear slacks: 1) I have short, stubby legs, and, er, am very curvy around the hips. 2) I'm short--very short. Skirts are impossible to fit around my thighs and butt and look nice, without being too big in the waist. AND, if I solve that problem, I then have to find it in petite.
The shirt thing: if it fits across my chest and around my biceps, the sleeves will ALWAYS be too long. I love 3/4 sleeves and blouses that are darted at the waist!
Note to petites: buy it in petite, or you'll look like a little girl playing dress-up! Trust me, just because it seems to fit in a regular size, doesn't mean the dimensions will look right. (Think Elaine from Seinfeld in that long, black dress!)
Luckily, I had several presentaions this past semester, so I wore the suit I got for Christmas in anticipation of me interviewing this fall. I tried several different blouses and shoes with it, got feedback from everyone (including pre-med advisor), got the slacks tailored, and am now ready to roll!
BTW, it's black pin-striped.