I just did this a few weeks ago... I was scheduled on CO from SEA to CMH but wanted to fly out the night before and while CO did not have a late night fight, NW did. The rep at the elite line initially said she didn't know if she could do it, but she checked with a supervisor and was given the OK. The ticket remained an eticket, but was swapped from CO to NW. I fully expected to pay a $100 change fee - but was told there would be no charge as a thank you for being a loyal CO customer.
Jennifer
[This message has been edited by jstockton (edited 05-11-2003).]