IMHO, skip the SQ lounge as OP's friend has 8 hours to kill. If it were me, I would hang out at the TG lounge until it closes, then get an invite to the KA lounge for the convenience of being close to the gate for departure.
LAX
If one doesn't have the onward boarding pass yet, doubt you can get into the TG lounge at all. More likely can only go to RCC as OP's friend is a 1P. The TG people sometime they say they have to photo copy your boarding pass.