Hmm leggings, I haven't recovered from the time I stopped a perfect stranger and kindly told her that her "dress" had ridden up above her hips, only to be told "I'm wearing leggings" Eek!
Also I like to tuck my tummy in so I like sturdy fabrics around my waist to give me a bit of support. The GD is very keen on jeggings, hers are very thick and warm and they add a little substance to her skinny little legs giving her more pleasing proportions just right with a knitted jumper dress.
My DD likes leggings but she has very thin spindly ankles and shins so she wears hers with knee boots. She looks daft in shoes or shoe boots with them (IMHO).
I'm tall. My fear is that a jumper dress on me will show an unflattering section of flabby mid thigh out of proportion to the comparatively slimmer lower leg. If I wear leggings with a slim above knee skirt the thick opaque fabric makes my lower legs look chunkier than I like and I don't like the look with any of my shoes or boots. I prefer warm tights with flats instead.
I haven't learned to rock the leggings and flowing skirt look. I know some very stylish septuagenarians who dress warmly through winter with leggings on under full skirts and dresses, but somehow I can't work their magic.
I have some very stylish black knitted wool long johns with lace trims at waist and shin. They're absolutely blissful and really good looking on (shapeless as anything off the body) but although these would look great on show, mine are always a secret underlayer.