The annual Shenandoah MTB Fest is one of the best and longest running mountain bike festivals in existence. The trails there are simply incredible, as is the vibe. If you have not ever ridden there, do yourself a favor and check it out. So much flair and flow, with such creatively developed networks with a huge variety. Several of the trails are featured in the yearly Shenandoah 100, and there are just a ton more all around. The camping is primitive, the communal meals are great for meeting more like-minded folks, there is a great swap meet (or Meat Swap as Crazy Steve Cihylik calls them), and lots of hearty end of season shenanigans. The James Madison Univ. Observatory is on site, too, and the dude that runs that is a real character who opens it up for the event.
Sorry for the short notice. Definitely one not to miss. Info here:
http://svbcoalition.org/events/annual/shenandoah-mountain-bike-festival/