Kelly Knob Overlook is about seven miles north of Newport, Virginia. From Blacksburg, take US-460W for 8 miles, turn right on VA-42 E/Blue Grass Trail, turn left on Clover Hollow Rd/State Route 601, and continue on it for 6.7 miles until it reaches an intersection with the Appalachian Trail. Primary activities include hiking and dog walking. Parking is free but limited to two to three cars. Water and restrooms are not available. Cell phone service was intermittent while on the trail.
The hike to Kelly Knob Overlook follows a 2.0 mile segment of the Appalachian trail. The first half mile is a steep incline after which the slope levels off. The following chart shows the relative change in elevation, starting at 3,100 feet and leveling off at around 3,600 feet.

The following picture illustrates the incline of the first half mile. If your kids can make it up this incline then the rest of the hike should be easy for them, minus a few rocky sections. I carried our daughter in a child carrier backpack so this first stretch was challenging for me.

The latter 1.5 miles rolls up and down gradually and includes both smooth and rocky sections. It makes for a peaceful walk because the limited parking means that you are unlikely to share the trail with a crowd of people. Follow the Appalachian Trail white blaze markers until you see a sign for the overlook.

From the sign pointing to the overlook, follow blue blaze markers 120 yards. Up to this point, the forest canopy is dense and, thus, provides shade on a sunny day.

We hiked this on very a hot and hazy August day. Our view was limited so I recommend visiting on a clearer day. Further, it felt significantly hotter at the overlook than it did on the trail so we did not stay long. I imagine Autumn colors would be a treat to see from this spot.

The overlook has space to set up a picnic but it is rocky and precarious to walk on top of. The following video scans 360 degrees from the center of the overlook.
In sum, the hike to Kelly Knob Overlook is fun, peaceful, and moderately challenging. Similar trails nearby include: