Originally Posted by
smackfu
More specifics: New York area to Thailand and Australia (separate trips).
For Thailand, Star Alliance is probably a better bet (Thai is one of the carriers here, as is UA, and both fly from the US to BKK). For Australia, I would say OW, since Qantas is a member there.
For simplicity's sake, start at the website of the carrier you want to earn the miles on (UA? AA?) and then ask for the destinations you want. They will show code-share flights.
See memberships of the alliances
for Star Alliance and
for OneWorld.