If you want separation from other sites, D36-D40 are on the back of a small loop, at the end of a road leading in.  Those are easily the best sites in the campground.  I saw them full of 35 ft+ motorhomes & 5th wheels.  D20-22 are also at the back of a loop but closer to other sites.  C-14-C16 are decent, too.
Avoid the ones on the inside of the loops--you probably won't fit in many of them, anyway.
There is a layout of the campground on the Reserve America site.  
The entire Big South Fork is amazing, and Bandy Creek is a very nice campground.  If you go in the spring, Leatherwood Ford is a great wildflower spot.  It is bear country, take appropriate precautions.