Two general rules with CO
1. It is almost impossible to get tickets on the dates you want, regardless of your elite level.
2. The closer to the date of departure, the more likely you are to get them. It seems like about 45 days before departure CO
will open seats up to reward usage.
Try looking at Northwest or Delta for availabilty, if you don't mind flying them. If you don't have the nerves to wait until 45 days before, try looking for upgrade awards. They'll cost you, but at least you'll have a guaranteed seat. Also, try calling and checking the web site, sometimes one or the other will be able to find you seats.
SkyTeam: The alliance for third rate airlines finally getting their act together!