I got started thinking about this topic after reading the article "What is Wrong With Cinderella" in the New York Times Magazine. The issue of modesty, or tzniut is one the I wrestle with fairly frequently. I used to dress exclusively in long skirts, and shirts that covered my collar bone and elbows. I felt that this was the way to be modest, but more than that, it sent a message about me to other traditionally observant Jews: that I was serious.
According to Semgirl, one should dress with modesty, but she is disturbed by the emphasis placed on this one observance over other virtues such as education, kindness, and dignity. Orthomom reports on a ruling in B'nei Barak that women should only shop at the 30 or so "pious" stores who stock only clothing that is appropriately modest. Beisrunner of All Your Beis addresses why the observance of modesty has historically been a female preserve. He suggests that it is because when the rules were made that women's desire was less of a factor than it might be now; they existed only as objects of desire, and not as people with desires.
I would submit that our concept of modesty has changed (as ably pointed out by Therapy Doc on Flam News), we, as a society have returned to the days when children were dressed as little adults, except this time the adult fashions that they are emulating are those of Britney Spears and Paris Hilton. Shira of On the Fringe, seems to agree, she states that the high incidence of less modest clothing is "evidence of a cultural shift." She even cites as an example a bat mitzvah girl (aged 12-13) who on her big day wore a low cut top that exposed her clevage.
I'm a big fan of dressing appropriately for the situation. Another comment that Shira made is that women used to dress in less formfitting clothes in professional situations. I for one, can't be sorry that those days are over. I like looking nice for work, there is something about looking good (and obviously professional) that helps me feel good about getting out of bed and going to work. For the record men's suits are a garment designed pretty much exclusively to make men look good. There is really no female equivalent, so I see the preponderance of attractive and well-cut women's suits as a step forward, an understanding that women are working in higher numbers and more prestigious positions, so they deserve the same accomodations as their male counterparts.
As for my personal dress, I still wear mostly skirts, but I now wear short sleeves, and sometimes allow my scapula to show. My feelings were that:
1) It is frickin' cold in New York. Some days skirts just don't cut it for warmth. G-d doesn't want me to freeze.
2) Wearing a long skirt and long sleeves in the summer makes me stand out, regardless of how covered I am, and draws (often uncomfortable) attention outside of New York where wearing a denim skirt is almost a statement of belief.
3) It is incredibly unfair that men don't have similar guidelines, how come they can swim, hike, bike, and ride horses in public, yet I can't? Unacceptable.
4) Why is it MY responsibility to keep someone else from sin? Also, I'm not really that egotistical to think that I am soooo hot that men are going to fall all over themselves if I show my elbows.
Granted, I think that the guidelines are a good starting point, but that the social outcomes are uncomfortable at best, and anti-feminist/repressive at worst.