PS: A note from my buddy Ron H. in Seattle on the purpose of a 200 K. Lots of sage advice here!
After riding a few of these solo with nothing else to do but contemplate the meaning of it all, I have come to the conclusion that each qualifying brevet has a purpose. Each distance has a lesson for the rider to learn or re-learn as necessary. Each distance is both an event and preparation for the next event.
The purpose of the 200k is to teach you the basics of how it all works. How to follow a route. How to get your card validated at controls. How to ride within time limits.