cloth can be a pain in the ass to work with. ive been trying to reproduce my one good skirt's setup. my main issue with my bad cloth skirts is they fold into themselves really easily -- my 'good' one doesn't and seems to fold at a more gradual angle rather than a harsh angle. i think it has to do with the way the vertices are setup -- decimating this down from 4k down to about 800 polys got it working well. 4k is a lot anyways probably. my 'good' skirt is 1400, decimating this one down to merely 1400 doesnt help, so depends. running a little bit of red between the legs in the front helps keep it down when im reclining back, too.
these are with short skirts too so im sure messing with a longer skirt is another ballpark