Kathleen, we must've watched the same WNTW episode because I saw one recently where Stacey was sitting on a couch and the camera must've been lower, and she crossed her legs, and I turned to DH and said "is that her panties showing?"
I'm 43 and only 5'0" with pretty good legs for a lady my age (if I do say so myself!). Because I'm short, with short legs, I always liked to wear minis. The proportion seemed good for someone petite like me. But in recent years I've gotten uncomfortable wearing minis. A big part of it is the fact I have teen daughters, and frankly, I want to look like their mom, not their teeny-bopper friend or college-aged sister.
A bigger part of it is the sad fact that age has made my butt droop. The minis look adorable if I'm standing, but as soon as I bend over - you see my knickers (as LouLou mentions!). My teen DD's do not have this issue. I can only ascribe the difference to age, and what it does to make parts droop.
Or if I sit down, I get all squicked out feeling too much bare skin on the chair. That may be an age issue too.
I still *occasionally* wear a mini (as Angie defines them) .... but only with black, opaque tights and FLAT shoes (like boots). I keep the rest of the outfit modest too. I own exactly two minis (a black one and a pretty green microcheck). I have not worn either in over a year, but I'm not about to give them away... just ....yet. I would not wear them out with my DD's. I would wear them for the right occasion like a hot date night out dancing with my hubby, or say, hmm... my 44th birthday.
Since I'm petite I do think that my skirts and dresses look best on the slightly shorter side. Exactly at knee (i.e., cutting midway through the knee cap) or an inch or two above. Yes, when I sit the skirt rises up a little bit more. My litmus test is how much bare skin is hitting the chair when I sit. We live in an urban area and take public transportation a lot, so it grosses me out to have bare skin touching bus sits and such. If the skirt is just an inch above the knee, it's usually fine (but I have a flat backside so ymmv).