This is a great question. OK, so I have played 1208 courses worldwide in my lifetime. Went thru the list and would say my total is 34 (excluding 9 holers). Of those 34, I would catagorize them as follows:
--"home" courses and clubs where am/was member--9 (played each well over 100 times)
--played >5x and memory strongly reinforced by TV golf (e.g. ANGC)--6
--played >5x times which was enough to remember--16 (of these 16 I would say 8 were basically because of the sheer brilliance of the design)
--played <6x but fully remember--3
of these 34 the fewest times I have played any is probably 4.
The last one of these that I played for the first time was Chechessee Creek in 2011. Being the ultimate in list chasers (and tending to work from the top of the lists down), my courses played for the first time in the last 2 or so years tend to be not a good as those played earlier (with some clear exceptions--e.g. Golf de Fountainebleau, Austin GC, Ohoopee, Mammouth Dunes, Cedar Rapids, Congaree, Huntingdon Valley, Askernish, Brora, etc.).
Of the 34...to me the most visually memorable (and easy routing to recall) has to be North Berwick.
Finally...I find that I do not remember the bad courses at all...I generally tune out after a while and can't wait till the round is over. With memorable courses, my senses are much more "alive."