I vote for the life experience and I think you may even find that technologically speaking Australia in some areas may even surpass the US.  They're definitely a "first world" country although pretty much no one anywhere in the world lives as lavishly as the average American.  Their medical system is socialized, so there may be more high tech equipment available across the board rather than each doctor's office/hospital having to ante up for it themselves.  Of course that might also mean there's less across the board too.  They are very much in love with innovation and while I was there, things like their cell phone usage were much more advanced than ours was (we've caught up now). 

Australia is often described as "small town American 20 (30 or 40) years back".  That's very true, even in a place like Sydney which is a major metropolitan city covering approximately a similar geography to the 9 county SF Bay Area.  The pace is slower than in most of the US, the people are friendly, especially one on one and they love Americans (again, especially one on one).  You should be very careful not to criticize Australia or Australians (even indirectly, or even if they insist).  It is ok for them to do it, but not for you as a "Seppo" (that means American).  They flip back and forth, often within the same sentence between "everything is bigger and better and greater and grander in the US" to "who the hell do they think they are?"  That takes a little getting used to but you'll get it.  Driving on the left is an experience, especially combined with the roundabouts.  I think the most important thing I got from living there was a much better understanding of global issues.  I had traveled pretty extensively, but being a tourist and living somewhere are quite different and I really came to realize how much most of the world is focused on the US, what we do, what our president says (stuff that wouldn't even make a news blip here), etc. 

You should also bone up on US History and Civics (even going so far as to get a kid's book on the topic).  You'll get a ton of questions from people.  EVERYONE that knew me at all, hubby's relatives, friends, co-workers, etc. all eventually asked me the following questions:

1.  Is it true that everyone in America has a gun?

2.  Is it true that people in America die in the streets for lack of medical insurance?

3.  Doesn't everyone in America have a washer, dryer and dishwasher?

4.  How does the CIA impact the lives of everyday Americans?

And finally, the big one- usually prefaced with "come on, we're mates, you can tell me..."  What really happened with the Kennedy Assassination?  Believe it or not it is hard for people in other countries to completely separate what they see about America on TV and Movies from reality and they wonder no matter how outlandish the claim is if there isn't SOME truth to it. 

I was also asked a lot of questions about our Rights- Freedom of Speech, Freedom of Religion, politics (I was there during the whole Clinton Presidue thing), our general prudishness (Sex in the City airs in prime time with no editing on regular broadcast TV there) and our holidays (Thanksgiving is fascinating to them).   I think you can have a great time, learn a lot about how they operate and learn even more about how we operate in contrast. 

Plus the bonus gift is that they almost speak the same language we do!  Hubby and I still have the occasional failure to communicate and still laugh over some of our funnier moments.  I won't give you all the details, but suffice to say you should not call something a "fanny pack".  Fanny is a very crude word and hubby about died when I said it the first time.  Fortunately, his family and small children weren't in the room at the time!

Good luck either way you go!

Tess