A quick addendum to my prior post, the circle asia rules are similar to the circle pacific rules, but require travel of course between Asia and the South Pacific. There are two tiers of circle asia fares: <15,000 miles and <18,000 miles. You can verify routing and mileage using the Star Alliance RTW mileage calculator, and you would have to pick a country of origin through which you would not transit twice (that makes SIN a convenient option mileage-wise but difficult to avoid transit; anything in Japan might, might throw you over 18,000 miles).