You could take a routing back via Asia, there are several nice beachy places there best reachable via HK. For example ORD-HKG-DPS-SYD or ORD-HKG-CEB-HKG-SYD or ORD-NRT-KUL-BKI (or any other place in Malaysia)-KUL-SYD.

Another thing to consider, if you're planning on flying Business Class, buy a separate ticket to Tokyo and start your RTW there, the savings can be significant.