I may have a chance at having an all-vintage session at a race track this summer. This is something I did in 2005 and will try to do again in 2006.
In 2005 I had no trouble filling up a group with nothing but old bikes. It was successful enough that I might arrange two of these for 2006.
Both events will be somewhere within 150 miles of lower Lake Michigan. Are there any people on this list that would be interested? Low stress, old bikes, and no 19 year olds on 600 supersports trying to run you over. It's a lot of fun.