From IAH, I would commute to MSP or DTW. They are both Delta hubs, so you have DL and UA flights to commute on. I think Spirit might go there as well. DEN would be difficult and you wouldn't be very senior there either. COS is not a good base to commute to because it is a maintenance base. All the trips there start really early or end really late or both. You'd have to overnight for all your trips on your own dime. Even LAX would be an easier commute than COS would be, even though the flight is longer.