Well, just some personal advice:
Want to have cockpit visit? CX or QF would be the best choice. Garuda I'm not sure but I know they have a very nice and new A330, used to saw it in Perth airport, really nice aircraft. CI I'm not sure but for sure if you are on A300, please expect a rather old aircraft. SQ and UA, forget about it.
So, the choice would be between CX, QF and GA. QF have a old and outdated 763. GA I'm not sure they have PTV or not. CX would be the best choice. Anyway, by considering a rather short flight, for me PTV wasn't really important.
I just went to HK 7th this month with CX via Perth and have a nice 30 minutes on the A330 jumpseat. A330 cockpit is just superb.
Hope this will help.