Leave SFO 12/8 on UA 152, 858, 146 or 136 (these depart 9a, 9.40a, 6.10p and 11.35p).

Leave ORD 12/11 on UA 131, 141, 147 or 155 (these depart noon, 3.10p, 4.44p and 9.25p).

$212.50 on Orbitz, $202.50 on ual.com. These are NOT Internet-only fares, so you can use certificates.

Other flights the same days are more expensive even though ual.com shows them with 9's across the board. I see no reason why you shouldn't be able to go standby on UA 809 (the 8.10a departure) Tuesday morning.

I booked 131 and 146 for 12/15. $182.82 including a trip to the very busy Michigan Avenue CTO to redeem my cert.