Tznius vs loshon hara--which is more important?

Last night, Chavie and I started learning the laws of loshon hara.  We begin by stating that the best prevention for loshon hara, or evil talk, is being dan l'kaf zchus.  Loosely translated, don't judge people.  Sounds fair.  It's an idea that has a lot of merit.  And it does come straight from the Torah.  So, no arguments from me.
But then, Chavie had to continue.
She goes on about the depravity of this generation. Specifically, how a friend's daughter is wearing a skirt above the knee.  Oh no!
Um, Chavie, didn't we just finish discussing the importance of NOT JUDGING PEOPLE!?
Over and over again, our Torah discusses the importance of proper speech.  Don't judge, don't slander, don't gossip.  I think there are at least twenty separate mitzvos (if not more) related solely to speech.  However, the Torah has four--count 'em, four!--mitzvos related to dress for those of us who are not the Kohen Gadol.  And one of those is by implication only.

1. Men don't wear women's clothes
2. Women don't wear men's clothes
3. Don't blend linen and wool.
4. (this is the one that's implied) married women must cover their hair.

 Nowhere does it mention skirt length.  When I mention this to Chavie she sputters about Rabbi Falk's sefer.  I've read it.  Now, unless Hashem has changed his name to Rabbi Falk, I'm going to pay more attention to a person's words and deeds, and less to their skirt length.