Thanks again everybody. I think I will play it by ear. This is a two leg trip for me, first leg LHR - EWR, then EWR - SFO so that is quite a lot of travelling. If I feel totally dead after the trip I think just for a painless trip to the hotel I'll take a cab, possibly a shuttle. If I still have a little bit of energy left then I reckon I'll grab the BART and walk.