Hello - I'm off on my travels again, this time around the world (and not a company jolly in sight

). This might turn into a request for some fairly detailed information when I actually get hold of my itinerary, but for the moment can someone tell me what leg room/comfort is like (generally speaking and for us poor sods in Economy) long haul on the following airlines?
Qantas
BA
Iberia
Lan Chile.
A/c is a mixture of 747, A340, 733 and 738, but long haul I suspect is going to be restricted to the 747 and A340.
Going eastwards, LHR - Hong Kong - Sydney - Wellington - Aukland - Tahiti (Papeete) - Easter Island (refueling only) - Santiago - Madrid - LHR.
Ta muchly, all and any info much appreciated.
LB.