How about this (on the return)
I've found some availability on the following:
Both on 1/9 and 1/10
TG 614 BKK 10:10 BJS 15:50 747 0 FS+ CS+ YS+
-> CA 983 BJS 21:30 LAX 17:00 747 0 FS- CS- YS+
Then you'd have to find a flight from LAX to SFO. (if you don't mind these airlines, if UA doesn't starnet block them and if you don't mind connecting in beijing.)
Found some same day on the 9th:
UA 731 LAX 20:30 SFO 21:45 752 0 FS+ CS- YS+
UA 263 LAX 22:30 SFO 23:49 320 0 FS- CS- YS+
Try that.
Billy