So, getting the AC booking number on the UA site is really not a problem, it's listed right under the reservation listing on ual.com,

but, I can't find any way to see any inventory of seats on the ac.com site, and am currently just waiting on the phone to try and get some sort of reserved/preferred seat, even would PAY for it at this point.

But, it really does seem that even though it books out and lists as a FLEX fare, that one doesn't get any of the FLEX fare perks?

When I called the United PremEx reservation number to inquire, well they actually just LAUGHED and said "good luck with that" and said if you want a better seat, probably try a different airline.!