Process of elimination:
If I lived in an imaginary world where it wasn't always clogged with tourists and didn't cost a ridiculous amount, I'd take Pebble Beach. Sadly, I live in the real world and the slow round times make it a non-starter. The same issues apply with Pinehurst No. 2, which is sad since it would be a real joy to crack the code of that course over multiple plays if only those multiple plays didn't involve spending so much time standing in the fairway with my hands on my hips while a pack of fat guys waddles from their path-only cart to their ball before ping-ponging it back and forth over the green three times each.
That leaves me with two options that would both excite me - The Dunes Course at The Prairie Club, or Crystal Downs. The Prairie Club would be wonderful to play every day with its astounding elasticity and overwhelming number of options on each hole. It could truly be a different course every day of the year and those huge corridors and high winds would give me a great platform to refine my ballstriking. But it's also a very challenging walk and while the collection of gentleman's clubs in Valentine is surprisingly large considering the size of the town, I'm sure they would eventually grow stale.
Crystal Downs is a slightly easier walk and has the better variety of holes, though less elasticity within each hole and fewer options on each. It's probably a little less interesting from a ballstriking standpoint, but much more interesting on and around the greens than The Prairie Club. Like Pinehurst No. 2, it would be a blast to spend the rest of my golfing years trying to crack its codes. Unlike Pinehurst, it's in an environment that I would love entering every day.
Gun to my head, I'm choosing The Prairie Club. Crystal Downs is probably the better course, but for me personally I'd rather compress the ball and carve it through the wind off fine fescue turf for the rest of my life than deal with the frayed nerves and mental demons that grow from putting and chipping the greens at Crystal Downs every day. My inner Hogan is just stronger than my inner Faxon, as this spring has proved beyond a doubt.