That's a manual tool, though. I personally use Illustrator whenever the need comes for something that is to be shiny, but my desire is for an automatic layout t

That's a manual tool, though. I personally use Illustrator whenever the need comes for something that is to be shiny, but my desire is for an automatic layout tool that can be driven from a DSL, Graphviz-style. Aside from efficiency (lots of diagrams for documentation or blogging), one benefit would be the ability to enforce a single theme (font, colours, etc.) across many diagrams, and push out new versions by tweaking the styles. Illustrator can't do that, and OmniGraffle is very weak at it. I tried using Sketch, which has a support for reusable symbols, but it's pretty terrible at it.