1) For those calibrating apples, remember that 1K is not UA's highest tier. Hasn't been for a few years, Comparing CO's top to 1K is a foil. Does CO have a truly elite tier that's similar to Global Services? That's not rhetorical. Do you?

2) Remember that UA and US do not have reciprocal lounge privileges, even absent the adult beverage factor. UA flyers get access to US lounges only when flying C or F, and vice versa.

While UA is the 800 lb. gorilla, I suggest that it will be much more interesting and fruitful (ongoing) to look elsewhere in *A for what's going to open up to you when CO joins it.