For me, I'd use the miles for trips Australia-USA, which is 60000 miles on UA and LH, 70000 for MX & RG, and if im not mistaken 75000 on AC. I had planned to do a crazy 29000 RTW with 25 segments for $2889 AUD, earning on 5 programs the 55555 bonus, but UA has the condition of one intercontinental roundtrip on a single airline, which has put a spanner in the works.

goodo