Retiring in Australia

My wife and I are retiring to Australia in 2010.

I hold US and Australian Citizenship wile my wife holds only US Citizenship and will be applying for a Spousal Visa for Australia.

In July 2010 we will have been married for five years.

My question - I understand that my wife can apply for the Spousal Visa either in the US or in Australia providing that she is in the country in which she applied when the visa is issued.

My question is are there any advantages or disadvantages in applying for the visa in the US and in Australia?

Thanks