Looking to book DCA/IAD-MEL and SYD-DCA/IAD in first/business. Was hoping to try NZ on one segment but pushes the price too high. Haven't flown to Australia in nearly 30 years! Narrowed down to the following:

DCA-IAH-SYD connecting to MEL on QF, all one ticket -- like departing DCA over IAD and the earlier IAH departure compared to LAX
IAD-LAX-MEL -- would rather avoid the late departure from LAX

Return also looking at SYD-IAH-DCA -- so much nice arriving at DCA even if it might be an E175
SYD-SFO-IAD
Rather avoid SYD-LAX-IAD since it arrives at TBIT

Any comments or advice? Thanks!