Welcome to FlyerTalk, prototypev.

Your best bet for fares and suggestions is NOT to look at SQ's website as they don't fly from canada anymore, and their website will give you what's 'official' and not what the lowest fare might dictate.

From Toronto, go to some of the asian travel agencies in Chinatown or Markham as they will have special fares from YYZ to either SFO, LAX, IAH or JFK to connect to SQ. No need to buy a seperate ticket yourself!

Alternatively, you may opt to fly with AC and connect to SQ at any of AC's gateways in Asia.

*Please note that your only options to upgrade on SQ will be restricted to the flights with 747 aircrafts operating. ie JFK to SIN or LAX to SIN, and you must buy a higher classed fare to allow the upgrade.

From YYZ, have you considered taking EK? They have the A380 and from what I heard, their economy seats seem as comfortable as SQ's.