Just a thought on the regular and priority postage system. Maybe AP plan to send the priority paid mail by air between states as they do for most regular large letters now, and send all economy class mail by road, which is much slower ????  This is the only logical way I can see for the system to work and would account for the higher cost for the faster postage. ( yes I know we already get air at the regular price now, but this is AP we are talking about ) .