I've done all of the above (on foot). "The Rock" can be reached by ATV, but its a super-easy micro from highway 101 also.
A bit south there are a few better ones. Search for for Sand Between your Toes, Spruce Hill, Beale Lake Geocache, Mardi Gras Topless, Hot Wheels in the sand. I have a bunch of caches in the area but like to stick to non-atv areas.
Mackie