Thanks all for your answers. They were very helpful. number_6, when it comes to knowledge and advice on flying F, you're the best!

I'll be flying out of BOS, but can route via ORD or NYC.

My once-in-a-lifetime flight is BOS-LAX-MEL in F, but I've been disillusioned about chances of getting a QF First seat without being high up in the Qantas frequent flyer scheme. It's also hard for me to book the 330 days ahead. My philosophy now is use the points on an international F flight I can get on, instead of just dreaming about something which seems to always be a longshot.