Amy Davidson has a nice piece on Michelle Obama's magisterial use of fashion as a tool of political as well as personal expression.

Michelle might have responded to that, as many women in similar, if less prominent, situations do, by being flawlessly proper—some unchallenged idea of ladylike, wearing dresses and suits and jewelry indistinguishable from Cindy McCain’s or Ann Romney’s. Or she could have affected dowdiness until getting to the point where, as Justice Sotomayor put it, ““They just can’t fire me over the earrings anymore.”
One shouldn’t need to go to Princeton (as Michelle also did [like Sotomayor]) to be treated with courtesy. But... There is the matter of having the right thing to wear, and of asserting—and even demanding—recognition for what the right thing is for you. Fashion can be a fight, and one not so divorced from justice.

I appreciate the way Michelle's appearance embodies the life advice I recall David Mamet once giving to somebody (however dudey his language): "If you're smarter than the other guy, be smarter than the other guy."