Then you need to talk about accruing miles


a lot of programs went to revenue-based earning. You may not care as much if you transfer miles from credit card

Redeeming miles: on same carrier, any specific routing, on partner carriers? Different programs have different strengths in different regions, and often it's dynamic. Usually it's not worth it to upgrade when flying a partner airline (only certain expensive fare classes qualify)



eg: japan airlines has standard PE cash upgrade.
https://www.jal.co.jp/en/info/inter/apopyug.html


UA had TOD options to upgrade with cash/miles/both for PE or J. Miles is usually standard while cash is dynamic, but it's harder to accure cheap miles on united by flying: https://www.flyertalk.com/forum/unit...rture-tod.html

https://www.flyertalk.com/forum/unit...united-48.html