Randonneuring is an organized form of long distance bicycle riding. And it's a blast. There is the benefit of meeting our fellow bicyclists, the interesting routes that take us to parts of our regions we wouldn't otherwise see, and the challenges. The distances are challenging, and the challenges ratchet nicely with ones abilities. Slower riders (like me) have the challenge of finishing within the time limit, faster riders can try to best their previous marks, or take advantage of the time for photo explorations, diner diving, etc.
Good description of Randonneuring and the rides (Brevets) are available on the web-sites linked below (don't miss the RUSA web-site), and here: http://www.randonneurs.bc.ca/introduction/intr_txt.html.
The national organization for Randonneuring in the US, RUSA - http://www.rusa.org, breaks the country into (approximate) regions, and in my part of the world the closest regions are in Portland, OR - http://www.orrandonneurs.org and Seattle, WA - http://seattleinternationalrandonneurs.org. Each of these is a good 3-4 hour card drive from the Tri-Cities, so, we're going to run a couple of Brevets (the rides) from the Tri-Cities this next year (under the auspices of the Oregon group).
The two rides we currently have schedule are a 200km Brevet on April 18, 2009 and a 300km Brevet on May 2, 2009. If we have enough participants, we'll expand our ride offerings in the next year and perhaps form a region. Stay tuned!