Hi
I am travelling to SF this Christmas and was quoted over €4k by my local travel agent (back in September). My sister, who lives in SF, suggested I use an internet company called Orbitz.com as she uses them regularly for travel within the US.
I got my tickets (2 adults one teenager and one child) for €2.3k - only downside is an extra leg (Cork-London-LA-SF as against Cork-London-SF for the higher fare). Hopefully, for that price, we won't be travelling "luggage class". Will be posting recommendation, or not, in the New Year depending on the journey!