I'm flying tonight on the 757-200 from RDU-CDG. Despite the small J cabin, there are 4 empty D1 seats with no one on the upgrade list. If I ran into this situation on say American or United I'm certain I'd be offered an option to buy up to Business, in fact I usually am. I'm quite willing to pay $500-750 to do so tonight but according to the ticket agent, gate agent and Skyclub Agent in RDU, Delta does not sell upgrades on this route. Seems a little silly to me as the inventory is going to spoil and people are willing to pay for it but I'm sure they have their reasons.
I'll have more legroom in row 36 as it is