Never stayed there but we had friend that did and they liked the place. It’s in Maryland so closer to you. https://www.cherryhillpark.com/

Other parks on the south side of town that I know about:

Prince William National Forest: https://www.nps.gov/prwi/plany.....ations.htm

Bull Run: https://www.novaparks.com/park.....ional-park

Pohick Bay: https://www.novaparks.com/park.....ional-park

Of course, the kids could tent camp in our backyard and you could have the guest bedroom....(we are really close to Prince William National Forest)