Originally Posted by number_6

The airside bus is not airline specific, it is for any airlines at LAX; the only requirement is to have a valid boarding pass for your destination terminal. You can transfer airside using the bus from T4 to Eagle and switch to a different bus from Eagle to TBIT (this is what the QF pax do, as can any pax flying out of TBIT). The bus runs every 20 min and takes about 15 min, so generally walking from T4 to TBIT is faster than using the bus, however staying airside avoids the security checks.

The T4 lounges are generally superior to the TBIT lounges however the AC has no food (while the TBIT J lounge has mediocre food). T4 F lounge has substantially the same food/drink as the TBIT F lounge and is much less crowded and comfortable. Similarly the T4 showers (both F and J) are much less crowded than TBIT.