Advanced typography in Omnigraffle
Omnigraffle does support advanced OpenType features, but it’s a little tricky to figure out where to find them. Here’s how:
Select text as desired.
Go to Format > Show Fonts (⌘T). This brings up the standard Apple font picker.
Click the gear in the bottom-left of the window that just appeared (upper-left in OSX Yosemite), and select Typography…
An accordion widget will pop up in a floating window. If the font in the selection is an OpenType font, you will be able to enable all sorts of typographical goodness. If it isn’t, then your pickings are much slimmer.
This little trick actually works in every program that uses the standard Apple font picker. That includes apps like Pages ‘09 (although not the latest version of Pages, unfortunately).