Have you experimented with topologically consistent simplification? In my experience, that's the hard part - otherwise when simplifying (e.g.) state borders, the borders no longer match up.
No, but that's next on my list! I'm familiar with at least one approach—identify borders shared by multiple features, simplify those independently, then stitch everything back together. I'm curious as to whether you can identify shared points and then use the average area of the associated triangles to prioritize removal.
I would be impressed to see an implementation of this. Topology is absolutely critical for serious GIS applications. Of course, ESRI makes it looks easy within their software, but I haven't seen what a basic algorithm looks like for this task. Good luck!
