SEA-EWR on AS then JFK-TLV on DL
Why would you drive across NYC during rush hour with a fairly small margin of error for making your flight (YYJ-SEA-EWR on AS/JFK-TLV on DL), instead of just redeeming YYJ-SEA on AS/SEA-JFK-TLV on DL?

Heck, you'll even end up in the same concourse at SEA (I think the QX Canada flights come in in S).