Going back to the SFO/LHR comparisons:
SFO seems to be a 'fair weather' airport.
LHR is an 'all weather' airport.
In Cat 1 conditions at LHR things run 'as normal'.
When down to Cat 1 conditions it appears that SFO cannot deal with 'normal'.
This is all useful information. We are planning a trip into the Pacific shortly that will require a stop on the North American west coast. From what I have read above, SFO has dropped to the bottom of the list of options...