First time doing RTW, never flown QF or CX or BA before.

Flying in business, AA PLT.

DFW - LAS
LAS - BKK
BKK - NRT
NRT - SYD
SYD - DFW

Have prices for Circle Pacific and OWE4. Any advantages to coming back through, say, LHR instead of straight back?

Looking for ideas on best routing and best flight experience, especially if I'm can use miles on AA segments to upgrade to first.