I flew Quantas LAX-MEL Business Class on a 747-400 in December. Went lower deck, returned upper deck. Upper deck is way better - quieter, fewer people, better service (because fewer people??!!).

I would recommend a Window seat, because you do get a rather large storage area next to you which can be used to stow the ol' laptop bag and shoes, giving you more leg space.

Have a good trip!