Originally Posted by
hughw
Just curious about how money + miles behaves in relation to just miles. ...
They are not necessarily related.
Mileage awards are separate "pricing structure" from cash ticket. Money+miles are cash tickets, with cash T&Cs. The miles in money + miles, is simply a cash credit for miles at 1 cpm.
Originally Posted by
hughw
I'm looking at a one way flight Y from FCO-EWR. Miles only is 40K, but money + miles is $631 + 54K. Why would it not only cost $$$ but even more miles than to use miles only?
Arbitrage opportunity? International OneWay cash tickets commonly have a penalty cost while award tickets do not.
Why are international OWs so expensive, such high fare classes?
International OW travel (such as TATL) is a case where award tickets are generally a better choice than cash tickets.