As a NW flyer, I feel DL is more hard to settle down with award tickets than CO.

When I book award tickets using NW miles on CO metal or DL metal, my WorldPerks number will appear automatically on CO's boarding pass along with status and elite access. However, it happened to me more than once that the same thing was not true on DL.

Just this past March, I had to call DL for a preferred seat assignment (DTW-JFK) on a NW award ticket. First the agent said she need my WP number since it is not in the record, so I gave it to her; then she said she could NOT verify my elite status in her computer due to the fact this segment had no potential to earn miles. Fortunately, I had another paid ticket with DL; so I asked her to access that reservation and input my WP number; then she said the computer recognized my elite status and she could go on and give me preferred seat on the DTW-JFK segment, although the computer still said nothing about my elite status in the award reservation. (That flight was cancelled on the day of departure due to snowstorm in NYC area and I got rebooked!).

CO must have something similar---I was once on a NW award ticket connecting from KL metal to CO metal. The inbound KL flight was delayed thus I missed the original connection flight. CO rebooked me in Y class for the next available flight and gave me the boarding pass showing my WP number with elite status. By that time, there was still a F seat available but I did not get it automatically (I did not push it through the phone, either; the phone agent said my information was there thus I need to wait). Then by the time I was asking the PC agent for help, she surprised me by saying that I was not even on the upgrade list, although the boarding pass did show my WP number and status. She did add my name on the list but it was too late. The last F seat on the lovely B737-500 was gone but in the end I did get WP miles for the CO flight.