I just check my co.com itinerary from time to time. If there is red ink anywhere, it is time to call. I have an intinerary where they changed 3 flights slightly in time, but changed equipment and fl. ##s. Needless to say, my seat assignments were screwed up, so I called and got it fixed.
My advice is to check your itinerary often (every few days) and if there is something you can't change on-line, give CO or your TA a call. Beats getting to the airport and getting seat 26E on a transcon :<
[edited for rotten spelling]
[This message has been edited by tvx (edited 05-10-2002).]