Originally Posted by
mattsteg
First you were asking about premium economy, now about business...this is all a bit confusing what your expectations are.
Skymiles can be redeemed on partners for economy or business. This has not changed recently. On partners that have an upgraded economy comfort type brand that books into the economy cabin and is then upgraded to using status or money, you can get that as well I believe. Premium economy products that book into their own cabin are not redeemable with skymiles, because delta does not offer a comparable product.
Miles tickets in general are not normally upgradable with cash. If you want business, plan to redeem for it or buy it. If you want PE, plan to buy it.
You mentioned redeeming on AA or buying with QF - buying is of course possible, but I do not believe AA offers PE redemptions either.
VA and QF both offer a proper premium economy (although paying for it is quite exorbitant). I believe that there is some way that AA Advantage miles are able to be used to get QF PE but some calling is required.