Thanks for upping my points. These prices are from Hipmunk and in CAD, for flights within 1-5 days of ETD, taxes not included. I've never bought directly from Hipmunk so I'm not too sure about whether it's okay to buy online from them, but the prices after tax are close to the prices quoted by Flight Centre.
I usually do a comparison between Hipmunk, Kayak, Flight Centre b&m stores and airline websites. My deciding factors are cost and mileage accumulation so I don't mind flights with 2 connections and US layovers. The flights with only 1 connection and no US layovers are much more expensive e.g. YVR-HKG-SIN upwards of CAD$2300 after taxes are included. You can verify that at Flight Centre stores.
If you're making frequent trips, better sense to stick to Air Canada and accumulate miles.
Again, thanks for the info. I thought the US layovers are a bit troublesome. Firstly, I'm unsure how is troublesome is the security clearance now. Even in Changi, back in 2003, when I board the flight for USA, the security check in Changi is strict. Secondly, I flew SIN-LAX-YVR. The UA plane from LAX to YVR is a small 8 or 10 seater plane. Quite scary for the first time because it is such a small plane. I prefer to have fly a jumbo jet from USA to Canada.
By the way, does Singapore Passport holders still require a visa to enter or layover in USA?