Last night I made a reservation on delta.com for flights in a couple of weeks. As usual, the system didn't let me select C+ seats, but then at the end of the process I had already been upgraded to C+ without having to go back in and change the original seat assignments. The system automatically assigned me to the farthest forward aisle C+ seats. On one segment I changed the assignment because I preferred a C+ exit row window seat (19A on the 75D), but the other three were seats I would have selected. Of course, if there had not been a lot of empty C+ seats I would have been relegated to middle seats.