Big Run Trail is a 8 mile lightly trafficked out and back trail located near Crozet, VA that features a river. The trail is rated as moderate and primarily used for hiking. Dogs are also able to use this trail.
Hiked this with my son. We didn't do the full loop - we did Big Run Loop, down to Big Run Portal Trail then found campsite about 0.5 mi down BRP.
As mentioned and with pretty much all SNP trails its big downhill to go out, and big uphill to return. Trail was in good condition, easy to follow, a little slippery with all the leaves.
My son (14) handled it ok with ~7 pack. Weather was absolutely perfect for backpacking!
I did this trail with my two dogs and it was okay. The trail is very well maintained, difficult to get lost. Not a lot of blazes, but that's okay because the trail is easy to follow. The most difficult part of the trail is the hike back up the mountain and once you're up (if you start from Big Run Overlook), the next two miles are pretty easy.
The only thing I'd say is that the trail path is very narrow and not much room to move out of the way - important to know if you'll be doing this with your dog. You cross a stream at one point, good place for dogs to get water, and then after that you'll be doing about 3.5 miles with no water access for dogs.
The views weren't stunning, it was very much like a walk in the woods. But, it had more solitude than other trails if that's your thing.