RV Park in Shenandoah Valley area

Lots of options. Country Way KOA in Luray is nice. The Jellystone in Natural Bridge as a river and lots of stuff to do. Wytheville KOA has loads of stuff to do but not sure about winery's there.

Harpers Ferry KOA has lots to do. Harpers Ferry National Historic Park is very interesting. Sites are not huge and some are not level, but the managers will work with you to select a site that works.
Luray KOA is another beautiful park. Not many activities, but does have a pool.
Rafting on Shenandoah River nearby.

While I've never stayed there, there is a Jellystone park in Luray with all types of things an 11 and 13 year old would like http://www.campluray.com/