Well, that was entertaining.
Bike on plane in giant plastic bag = awesome. Virgin were completely unfazed and the bike was fine (although there's not much could go wrong anyway).
Cycling round Silicon Valley was a lot more fun that being sat in a cab or a hire car. It puts the UK to shame for bike friendly roads: there are lovely wide smooth cycle lanes almost everywhere, the train has an amazing dedicated bike carriage, and car drivers could not be more courteous.
I managed some lovely rides up to Skyline during the week (46:16 is a bit too high it turns out). On the Saturday I gave up trying to get anywhere interesting - it was raining heavily, the forecast for Marin County was hail/thunder, and the local bike shop were not going to rent anything out in that weather. So I just went for a local ride up a huge hill in the rain.
I'd definitely take a bike with me again. Gears might be nice next time, although the flip-flop thing worked better than you might expect.