I absolutely love the Caulfield Racecourse, mainly for its vast open spaces accessible to the public. I especially enjoy walking into the central park area which has a lake, walking track, bbq facilities and spacious grasslands.
Obviously, this place is only available on days in which the racecourse is otherwise not used by any other function. This makes it all the more enjoyable because it feels like it's just there for the few lucky people who happen to be there on those occasions.
Make sure you get down the middle section of the racecourse as often as you can. It is a truly relaxing place or an ideal setup for personal exercise.