Originally Posted by
tomh009
If lounge access is a big factor, you probably want either *A or OW, as ST provides lounge access only for the top tier, and then only for international flights; *A and OW give access at the middle tier. Within *A, UA and US also limit each other's members' access on domestic flights, but non-UA/US *Gold members do have access.
It's the same with AA - they don't give you domestic lounge access, you have to have mid-tier status on other OW carriers. However there are often restrictions on maintaining status on non-US airline programs when you live in the US, for instance that you have to fly X number of flights segments on the actual airline.
Also worth considering the effort you want to put into chasing alliance partner airlines to credit miles. From my experience, OW works most as an "alliance". Skyteam will grudgingly credit partner miles if you chase. Star Alliance seems like an alliance only in the minds of its marketing agency when trying to credit flights on partners, and you end up giving up. Of course, others may have experienced differently.
The financial solvency of the airline you choose to focus on is also important. My first few years out of university I travelled a lot through my job on Ansett (*A), only to lose top status and hundreds of thousands of points when it went went bust in 2001.