ITA`s month long search, revealed many possibilities at around 2100/2300. However, I would not hesitate to try other SE Asia cities.

Aug 12
United Airlines Flight UA838
All Nippon Airways Flight NH7018 on a Boeing 777 (jet) in coach class(operated by United Airlines as Flight UA890)
United Airlines Flight UA6498

Dec 10
United Airlines Flight UA6517
All Nippon Airways Flight NH7019 on a Boeing 747 (jet) in coach class (operated by United Airlines as Flight UA891)
United Airlines Flight UA853

PS Is August the double mileage month?

PPS Aug 11-Dec 9/10 with United metal and flight numbers is pricing at $2,194.