My mother in law is the same way...she wears t-shirts with Winnie the Pooh on them and polyester pants in colors nature never even dreamed of. At least since we moved out of her area she's quit buying clothes for me as gifts...
I think I have pretty nice legs, too, and I have the same problem finding clothes that show them off. I also have the added problem of being 5'5" -- which isn't very tall at all, but apparently the designers and makers of plus size women's clothing think that all big women are 5 feet tall and shaped like chubby little butterballs. Most pants and jeans are too short for my legs, yet if I buy the tall sizes they puddle around my ankles.
And I'm shaped like two apples stacked on top of each other -- round on top/small waist/round hips/slender legs -- so if I buy pants that fit me in the waist, they're too small for my hips; if I buy them to fit my hips and belly, they're too big at my waist; and no matter what I do, the pants legs flap like empty sails.
And I understand what you mean about plus size clothes being too old...I may be 30, but I'm not ready for Grandma-clothes just yet.
And don't even get me started about trying to find fetish-wear in my size...the only place I've found so far that I like is
Lady BWear ...