I would stay away from UA/CO right now. I'm considering a status match to DL before my next trip because of:
-under CO's upgrade system, I have only had 50% go through on CO metal versus 100% on UA (as a 1K). Right now the evidence is that it will be worse.
-regional upgrades are basically non existent now since they moved to 2 on the first 100 BIS versus 2 every 25,000 per quarter.
-MP miles have been significantly devalued the last 2 years plus now lower elite tiers won't earn 100% bonuses.
-The permeation of the ERJ + barbie jet on feeder routes is becoming too much to stomach.
-no real wi-fi, just 'plans'