I have been a PGA Member for over 35 years and have been blessed to play many of the greatest courses in the world, but that answer is an easy one for me. Pine Valley is the best private course I have ever played. I have only played there once and that was 33 years ago but I have a vivid memory of every hole and shot that our foursome played that day. From my view Pine Valley has great hole sequencing, and is a fantastic design. The course is difficult but fair in every way.
I have played many courses with nicer clubhouses and locker rooms but no other design is as memorable. If you ever get the opportunity, this is the one must play in Golf!