Sorry for the bump and hijack, but I have the same question. At the moment I am focussing on get *A Gold first, but if there is a relatively easy way to get Sapphire on OW, I'd like to hear about it.

My main interest is in extra luggage allowance. Seeing as I've been based on Japan for the past few years, have family living in Hong Kong, and am from the UK, JAL, BA, CX are immediate contenders (quite a few family members are on CX's Marco Polo).