Do Delta Platinum members receive complimentary upgrades on AF international flights? My fiancee and I are planning our honeymoon to Bora Bora (she is the Platinum). Trying to decide between the United flight from SFO or hopping down to LAX for the Air France flight. If we book in Premium Economy is there any chance we'd be upgraded to business? (Or would she and I'd be left behind? which I'm actually fine with)

The other option I'd like to investigate is upgrading with miles, but seeing the flying blue miles necessary for the flight itself, I don't have much faith it would be a reasonable option.

Any insight is greatly appreciated.