Having tried in vain to plan a similar leg down the west coast , I can confirm that the seasonal QF flight (Jun-Aug and Dec-Jan last year) between SFO and YVR is the only xONEx direct option covering the cities between SFO and YVR. Otherwise you'll have to do something like go via ORD (!!).

On another note, if you're travelling on a premium ticket you might want to consider CX going JFK-YVR, rather than going LGA-YVR, as its a nice long haul 747.