All I know is that ex-USA raffles class is among the most expensive which is why other than YVR-ICN-SIN-ICN-YVR in raffles, I have never flown SQ's USA flights in Raffles or F.

SQ really has good F deals ex-BKK (recently booked F for BKK-SIN-MEL rt for a ridculous price of only $2800 USD) and really good raffles deal ex-HKG.

One really bargain fare ex-USA one can find is raffles LAX-TPE-LAX which IIRC only runs around $2,600 USD.

Try contacting www.toureast.ca with offices in Vancouver and Toronto as they may be able to offer you special deals like they did for me last year.