Here's another nice fall biking event: The Fall Foliage Festival in Staunton, Virginia, about 3 to 3.5 hours from the D.C. area; 2 hours from Richmond. Routes of varying length. October 16-18. Mighty perty scenery, especially in mid-October when the mountains are decked out in reds, oranges and yellows!

More info: http://www.shenandoahbike.org/