SFO can be a cluster when the weather goes grey (and surprise, surprise, that happens a fair amount of the time). First flights on the chopping block are the west coast commuters , think SFO <---> PDX, for instance. I live in PDX and fly to SFO at least once a month and I've grown to really hate connecting through SFO. I'd leave a minimum connection time of 4 hours through SFO. In all honesty, the best route I have found is either YVR or at a push SEA. It all depends on which airline alliance you favor. For me it's Star so AC into YVR and plenty of Q400's from YVR to PDX would be my preference. If coming from Europe ORD, IAD and EWR (Eww, I know, but sometimes it just works out that way) are all better options than SFO, IMHO.
Oh and forgot to add, there is a direct LHR-PDX on Delta that started in May....