* I am expanding the thread discussion to cover historical liveries of both airlines now. Images are now being posted in the wiki post above*
I guess being stuck at home provided a lot of time for me to surf the web, and I came across images of various CO and UA logos.
Interestingly Saul Bass did design the logs for both UA (1974) and CO (1968) at certain points in time.
Someone on the web expressed the globe logo was dated and does not reflect PMUA, and designed a combined Saul Bass logos (see the last image in this post). I am not a designer or artistic, but I thought the combined Saul Bass logos does not look bad, and with the some tweaks and balanced colors, it may still look better than the globe.