Sure I realize that, just stating my experience as have others. Gas is gas, but at that particular time "something" between the two fuels made a difference. Fast forward to the present and you will probably hear of similiar stories (anyone care to share yours?) of how one gas performed better than the other.
I usually buy at the station with the lowest price, and I’m not aware that that's ever caused a problem with any car I’ve owned. However, there’s one tip I read many years ago that I’ve taken to heart. That is to avoid fueling at a station which is receiving a tanker load of fuel, because of the sediment that can be churned up and find its way into your tank.
Not if you consider the SF bay area as part of 'Northern California'. I retired from Chevron in Richmond as an instrument tech and our neighbors were operators at Valero in Benicia and I drove by Union refinery every day to work.
Are you sure the Prius is compatible w/ E85? From the owners's manual, p. 563: " Toyota does not recommend blended gasolinel Toyota allows the use of oxygenate blended gasoline where the oxygenate content is up to 10 % ethanol or 15 % MTBE." Could it be a regional thing (i.e., in the Midwest, where E85 is more plentiful)? This would surprise me.