Best value would be for BA miles on AA flights.If its UA make sure it departs JFK & not EWR.
Dunno about SFO, but I know there are still PMCO lie-flat 752s running EWR-LAX.
Not all flights
How about from jfk to lax or jfk to lax?
I didn't say on all flights, but to rule out EWR altogether for J is wrong.
some people prefer it to the First Class cabin.