If I fly westbound in economy, I try to do so on a daytime flight if possible, since I almost never sleep well in coach and this makes me suffer from jet lag for several days after arrival. If it´s a daytime flight arriving in the evening, I can go to bed when I arrive and simply sleep off the extra-long day I´ve had. The price for an extra hotel night is worth it IMHO.
At least this is what I´ve done for transatlantic flights - I assume though that this is also true though for the super-long flights to OZ as well.
Yonatan