My idea of a "fun" course to play is probably best captured by Sand Hills.
First you have the visual appeal, Vistas, raw bunkering, contrasts between fairways and rough.
Most importantly however it is a very challenging course with multiple strategic opportunities but is not severely punishing. I'll explain what I mean.
The par 3's are the most exacting holes on the course and are the most punishing for a missed shot.
Most of the par 4 and par 5 holes have very wide and generous fairways. There is always an A position which you should hit to in order to play the hole well, but their are always options for a shorter hitter too. This means that a poor tee shot usually still has somewhere safe to land. The challenges increase as you get closer to the green, however with a shorter club in hand it is less likely that you will hit a foozler off into the prarie.
The bottom line is that this creates a course where you have a smart and challenging shot from every poisition from the tee in, but if you miss, you will likely have a decent recovery shot.
I could play that course every day forever, it is like a playground.