I posted earlier in this thread about CO redemptions that would work. EWR-YVR for pretty much any date gives you a refundable ticket (so no change fee) for ~$1750 + $200 taxes. You will need to call up CO to change the ticket and request the remaining value to be put on an e-cert which will be valid for one year. Others have posted about workarounds to extend the date validity of the e-cert (basically you need to purchase a refundable ticket slightly more than the value of the ecert, and then cancel, which will result in a brand new ecert with an additional years validity being issued).
SFO-YYZ gives you a non-refundable ticket ~$1790 + $200 in taxes (you have to play around with dates to get this price).
The refundable to lower value new tkt with e-cert balance is a hit or miss thing. Personally, I would not try to save $150 and then risk having the SNAFU which did happen.
I have known an actual case that the e-cert balance although was requested, and confirmed by the CO rep on the phone, it did NOT happen. The balance of value went back to TYN credit card. The person who got burnt on this, had to call TYN to sort that out, and waited for the partial refund of his TYPs which amounted to 50K. He finally got a call from TYN on Friday that TYN rec'd credit from CO, and his 50K pts would be refunded to his account shortly. He hasn't seen the 50K yet.
To extend the date of e-cert, all you need is to take advantage of CO's 24hour full refund policy - you need to call in to cancel and the web support will then notate the ticket that no change fee would apply. So when you book against the cancelled ticket next time, there would be no change fee. And if there is residual value from that, a new e-cert is generated with new date. The regular rep cannot handle it when it is booked with e-cert. S/He would transfer you to web support agent for handling.
I am not sure e-cert resulted from cancellation of NON-refundable can be used to book refundable. As it is clearly stated in Fare Rules that credit from non-refundable cannot be used to book refundable, at least for the initial booking. Dont know about subsequent bookings though. May be the system can only keep track for the initial usage of the value.