From all of the different recommendations that people have posted (here and elsewhere) it seems there is no one way to cook prime rib. If some people swear by the hot oven method and it works fine, and other folks swear by low and slow and it works fine, that tells you something important about prime rib. It seems as though prime rib is pretty versatile and tasty and the main thing is season well and really just to not to over cook the meat.
FWIW: I just picked up a small CAB prime rib for Christmas. Will be smoking at ~250 until IT of ~115-120, pulling, resting for a moment, then searing on the grill for a couple seconds per side...rest, slice, and enjoy! Oh, and buy a large enough piece of beef for planned-overs. The stuff not enjoyed the first night makes for great sammiches (sliced thin with some sharp cheese, fresh tomoato, and horseradish) the next day!
Merry Christmas Brethren!
Bruce