Interesting! I'm a nerd and actually keep a spreadsheet of my current measurements along with the measurements for different sizes so I know how many inches I need to lose before I fit into them.
One thing that annoys me is that by measurement, my hips always fit into the next size down sooner than my waist. This seems weird to me since I have a pretty small waist in comparison to hips (borderline hourglass). So when I actually try on the pants, the hips will fit and the waist will be gapping awkwardly, unless I'm lucky enough to find some jeans with a specifically "curvy" fit.
Ahh, well. Shopping for pants is always a pain. lol