Couple of quick thoughts:
- MFU? (Would have to fly via BKK or SIN though and no RTW routing)
- Buy a OW Visit Australia pass for the local flights
- Buy a RTW in South Africa and start there... (around 3500 if booked on AA in D, you can use your miles to get there.)
Last is probably the most economical. You will earn a gazillion miles for your HHA, keep status and have another free holiday of a lifetime next year.