BLM has the most well-maintained campgrounds in Alaska, and Marion Creek is among the tidiest.  It's very clean and quiet, with reasonable privacy between spots and well-placed pit toilets and bear-proof trash cans.  The surrounding mountains are quite beautiful, and Marion Creek itself is lovely and looks very fishy (although I did not fish while there).  I stayed two nights, and would happily stay there again while traveling the Dalton.