I've put together a fairly extensive sizing chart, both for consistency across my own pattern line and as a resource for other designers who might find it useful. Marnie's awesome post on using excel to manage sizing patterns (which was really helpful to me since it's been a couple of years since I worked in an office and was familiar with excel) alongside a ravelry thread on sizing patterns finally prompted me to get around to doing this. You can find gif, pdf and excel versions here: Hope it's helpful.

The first Snow White

Hit with a John Knox Space Bonnet!