I'm looking at travelling between 1 & 3 times per year business or mixed business/first from Sydney to the UK or the USA on Virgin or Thai flights (codeshared where applicable - eg the Virgin Syd<-> LHR is really codeshare on Malaysian metal).

I've been checking out the various StarAlliance FF programs and the most interesting seem to be Thai (retain status 2 yrs) or Singapore (partners with Virgin as well as StarAlliance). The other main possibility would be United. Thai and Singapore also seem to make most sense given that Syd <-> Europe uses one or the other as a hub.

Has anyone done this comparison already? Are there any major pitfalls to be aware of in going with Thai Royal Orchid (eg can you get lounge access if you take a United flight domestically in the USA?). I'm currently moving on up in the Qantas (ie OneWorld) program, so haven't ever looked at S*.

Thanks in advance for any help