So I think I've figured something out, and I thought I'd pass in on in case there's anyone out there with the same fit issues as me.

I mentioned a while ago that I'm spending a lot of time in the letterpress workshop, and need black clothes. My old black skinny jeans are super comfy but getting faded. I wanted a new pair of black skinnies. I found a nice, very comfy pair of R&B 'coal' skinnies, but the size 24 that the SA convinced me to buy left red welts in my hipbones and after a half hour of wear, I couldn't wait to get them off my body. I exchanged them for a size 25, which are super comfy. HOWEVER, they slide down, as many skinnies do on me. My old pair slide down too, and I can tell they're way too loose in the waist and seat. I've just never bothered having them taken in.

Anyway, I took both pairs (old and new) in to have the seat taken in along the back seam. IT'S MAGIC. Now they don't slide down! I think the issue is that with an 8" or 8.5" rise jean (because, let's face it, good luck finding a 7" rise these days), the waistband is higher and so what fits across my bum is too tight across my hipbones and belly. I don't curve in at the waist much; I'm pretty columnar. With 7" rise, the jeans sit low enough on my hips that this is not a problem.

In other words, my small flat butt doesn't work for most skinnies! To fit at the waist, the seat is too loose. And because I have slender thighs but muscular calves, the skinnies grip my calves tightly and the too-loose top part of the jeans can't keep them up.