For the majority of my award use, I have used United, and to a lesser extent, Alaska. I have always appreciated United's "Standard Award" which gives last seat availability. Domestically it is 25,000 miles each way in coach and 50,000 each way in first (on 2-class aircraft), double the Saver award price, but you can get onto any flight and it is also easy to change flights. Since CO has the same award price levels, I assumed the awards would function the same, but I definitely see flights that are available for purchase that don't show up when I do an award search, even under the EasyPass, which costs the same as United's Standard awards. I haven't seen much discussion of this, nor what policies will be adopted by the merged airline - but I sure value the availability of United's standard awards.