I haven't found a good way to sit without exposing my panties. I don't know how the GG's do it so well! I keep my knees together tightly but that still leaves an area where my skirt is stretched across my thighs. Crossing the legs is the only thing I can think of but I'm not sure what is showing underneath then since I can't look there.
I will point out that this is only a problem with my 12" skirts. The longest I have are 20" which isn't a problem, just these minis which are my favorites.
SO says I have better looking legs than hers so I like to show them off!