Yeah . . . a major pain. Just had a fantastic conversation with an agent at the 1k desk. Walked me through how they release seats based on revenue management, with cargo playing a large role.
I have it narrowed down to 2 flights. UA851 which has ~50 business class seats, 13 taken (11 sold / 2 upgrades released to 1Ks), and no one on the waitlist
OR
UA 2166/UA888 ORD-SFO-PEK which has ~50 business class seats AND 24 Premier Plus seats. So 74 comfortable seats. No business or PP seats have been released on this flight and only 3 business seats were purchased.
I was leaning toward the latter, but the agent said that since they have already released 2 seats on the first flight, they have probably met their revenue target and are likely to release more. So, I think I am going to roll the dice and take the direct flight. This is AGONIZING!