Set expectations low at this point that the 789 will be operating - Other threads report FAA has issued an ETOPS AD for some aircraft with the Trent 1000 (includes THAI) - this limits aircraft to not more than 60 minutes flying on 1 engine. See:
https://www.flyertalk.com/articles/t...l&utm_campaign=
The Boeing Company AirplanesBest outcome would be a change to 77W/359! You may like to look at the varying seat maps, and select seats that 'work' for you as a couple no matter the type concerned.