Neil,
Fair enough, I wasn't aware there was a 'theme'.
If I had visiting friends, the courses I would say they absolutely must play are as follows.
VIC: RM (both), KH, Woodlands, Victoria, Peninsula, National Old (there are many more, but these I think are 'must plays')
NSW: NSW, Newcastle, Ellerston (if they can get on!)
Then of course Barnbougle, but one can assume they are coming back when the second course is open. I also reccomend Royal Adelaide and Royal Queensland, but understand the difficulties of air travel to see just the one course.