I am a CO Plat Elite and a NW PLAT Elite.

Northwest has empowered the Elite line to handle flight irregularities, upgrades and anything else that may need attention pertaining to NWA flights.

Continental has disempowered the Elite line agents. You get explanations such as "The computer handles all upgrades, we are not allowed to" and they have more excuses why they (CO Elite Line agents) cannot assist in resolving issues.

It's your choice, I'd recommend Northwest.

Good luck!