I'm sure it's been commented on here before, but the flipping of the 10th (old 18th) green and tee, making it the new 10th hole, and thereby making the old 17th the new 18th, was one of the best major changes to a classic course I've ever seen. These things often (usually?) get screwed up, but I really like this change. And I think the new 18th (old 17th) is one of the best finishing holes in golf.