I usually just go into Nordies at the beginning of winter and buy a whole bunch of different ones to find what I like best. I have found that sizing up reduces the crotch at the knees effect. But I have long and thickish legs. I love tights and skirts/boots in winter. It's practically all I wear for work.

I tend to go for thicker ones - some of the ones that Nordies link has seem more like nylons than tights to me. The point is warmth and durability. Some of those look like they'd be more appropriate for Vegas....