- Partner award availability online. They don't have everybody, but they have quite a few, and it makes searching for reward travel a lot easier.

- Mix/match awards. Both in class of service, as well as award type (Saver/EasyPass). Not all carriers do this, and it comes in handy sometimes in tough availability situations where you don't have to overpay for something you're not getting.

- PDA Site.

- Priority Bag Handling. Most everybody tags bags like this, but CO seems more consistent at actually honoring the priority tags. Probably the only carrier that gives CO a run for its money on this one is DL.