Worldly Thoughts - Regionalizing Peering

  Drawback: It is technically challenging to create an automate
  system to regionalize and create appropriate filter lists.

I always did enjoy a challenge.

It's really pretty trivial up on the whiteboard. My model includes BGP
confederations to define regions. In the absence of enough IP Addresses to
divide your allocations by confederate AS, I am fairly sure the use of
communities could be used to hack the distribution of more specifics into
conforming the way you want.

This is all from memory. I haven't revisted this model much since I
developed my first one late last year. Maybe they're some new knobs which
make it even easier.