Wow, that's a tough one.
For me, I relate clothing to type of work/job, but not intelligence when it comes to suits. I'd actually be more inclined to think of the look Mel brought up with her kids, just people not too worried about fashion.
I haven't been around large groups of females since I was in grade school/Jr. High, so it's hard to even think of a group of women and think of something that might make one stand out as "looking intelligent".
So, all I've got is they have more of a "girl next door" look, and they tend to look a little more "serious" than average.