Nice paved path out to the arches. The petroglyphs were pretty but sadly vandalized. Lots of beauty. The road out is car friendly.
If you are going down K7000, definitely take the detour to see Grosvenor Arch. It is a five min flat walk, and the arch is spectacular. Walk all the way underneath, on a clear blue day your pictures will be awesome. There is a small parking lot, and a toilet as well. If you are not going down K7000 road anyway, know that this is a 30 mile very bumpy twisty unpaved ride. Perhaps there are other lovely places you can go in the time you'll drive to the arch and back.
Beautiful arch! High clearance vehicle a must if coming from Cannonville side if there has been rain in the last week. No hiking required.
I went late in the day and was fortunate enough to be there all alone. I drove my dual sport motorcycle up Cottonwood from big water and it was an epic dirt road ride, highly recommended.
It's a bit of a drive, maybe ten miles, over a fairly well maintained dirt road. No off road capability is needed to drive it. We saw only one couple there during our one hour visit. The walk to the arch from the parking lot is 200 yards on a sidewalk. The arch is grand and imposing, while the setting is serenely quiet.