Dare we conglomerate the ideas expressed regarding individual courses?
It seems that a fun course has as many different shots as possible, including up and down hill, bank shots, unique shots, run up, high spin, low trajectory, cut and draw, etc. That would apply to short game with a variety of recovery shots presented, and putting, too, with one himalaya type green, some flat, etc.
If I can imagine a shot as a golfer, it should be on the cousre.
It also seems the course should be a something less than a relentless test of golf - there should be breather hole/shot here and there and there ought to be a way to play where you are assured that you won't find water, etc. even at the expense of missing the green. Even a shot to an island green for max precision is fun once or maybe twice per course. But a steady diet of small targets and narrow fw appeals only to a few.
From an old thread, I will add that there should be some lag time between striking the ball and knowing the result! That could be from carry hazards where you have to wait until the ball lands, semi blind shots, or firm and fast conditons.
A dash of firm and fast is always more fun than soggy, partly for the reason above. I imagine if the course was baked rather than firm, it would not be quite as fun.
Ditto the wind. It must be present to be fun, but not so strong that you can't judge shots or stand up to hit them! Not that anyone can control that......
The course should be somewhere less than the max length you can play - because its always hard to play a good shot at long distance constantly. If you COULD play at 7500 yards and reach the greens, I think 7200 would be fun, while 7600 would be a test. If you could play 6800 yards, then a course set up at maybe 6600 yards, etc. Long courses just aren't that fun (for most)
Of course, state of mind is difficult to control, but essential. For example, I could rarely be at the golf course without a unpleasant send off from the ex. Kind of hard to enjoy yourself when you know you will catch hell when you get home. For that matter, I always play badly when I "know" I should be getting some work done. If you can tell me how to control those things as a gca, I would try!