SFO-NRT in NH J is 92k UA miles. It would be 100k Aeroplan miles to fly NH F. I get that NH has newer hardware in J/F... if you get a plane with that newer hardware (it's unobtainium out of SEA, and frankly I'd rather have a JL Apex Suite than NH's seat out of SEA).

If you'd like some comedy value, price DL DeltaOne out of SEA on SEA-HND using SkyPesos sometime.

AS has fairly few value redemptions left on the list where they offer clearly better value than some other program (for instance QR J to DOH is cheaper on AA than AS). CX premium cabins are also mostly made out of unobtainium, that leaves you, what, unicorn QF J/F seats? Oddballs like DE to FRA in J or FJ J? Maybe SQ given that SQ's phone agents are a horror show (but lately AS's agents aren't much better?).

Frankly you might as well spend the miles and move towards transferrable point systems unless you're locked into AS for whatever reason (SEA-based, Alaska-based, collecting bunches of miles flying paid BA F/J, whatever).