You might not have enough miles for this but a very substantial oneworld experience could be the following itinerary:
LHR-USA : AA F (75k Avios)
USA-HKG : CX F (105k Avios)
HKG-SYD : QF F (75k Avios)
SYD-NRT : JL F (75k Avios)
NRT-LHR : BA F (90k Avios)
Total : 5 F products (420k Avios)