If you do upgrade, you should be able to select your seat at the time of booking except for BA flights. I always travel in business on long haul flights. In my experience, not all JY agents are helpful when it comes to upgrades. Make sure you ask for your personal booking number if you do upgrade, so you can check in on line.. I haven't flown BA premium class for a long time, so can't comment on that , but having recently flown business with them to the States and back I was appalled by the poor standards of service. The new cabin layout is very cramped. It cost an extra £130 to preselect my seats both ways. I gather my fellow travellers had a dreadful time in economy. I certainly won't be considering any future long haul holidays using BA flights. All the other airlines I upgraded on were fine, even Air China was so much better than BA..