Originally Posted by imagineertobe

As a first pass:

Europe
FRA, 11: AA, BA, CX, AY, IB, JL, LA, MA, QF, RJ, S7 (the only I can think of with all active members)
LHR, 8: AA, BA, CX, AY, IB, JL, QF, RJ
CDG, 8: AA, BA, CX, AY, JL, LA, MA, RJ

N. America
JFK, 9: AA, BA, CX, AY, IB, JL, LA, QF, RJ
LAX, 7: AA, BA, CX, IB, JL, LA, QF
ORD, 6: AA, BA, CX, IB, JL, RJ

Asia
HKG, 6: BA, CX, AY, JL, QF, RJ
NRT, 6: AA, BA, CX, AY, JL, QF
SYD, 5: BA, CX, JL, LA, QF