Thanks everyone! I went searching and found availability for a single person in Club World for a return journey from LON to SJC (actually that's where we're ultimately going anyway - silly me just thought that SFO might be more accessible!) Unfortunately there are 2 of us travelling though. Using money plus Avios it would have been 125,000 Avios plus GBP570 for a return ticket in Club World (with other options for a reduced Avios spend as I up the money invested). The thing is that these reward flights seem to be so rare they are an almost mythical being - is that correct or do I just need to persevere and be lucky?