What was causing your flats? You live in Northern CA, I don't remember thorns and thistles being a problem there or are they?
The best flat resistant tire I ever used was the Specialized Armadillo All Condition Pro, with these you don't have a need to use a flat liner or heavy thorn resistant tubes plus they have the strongest sidewall in the market to guard against damage. I use to live in Southern CA and goatheads were the big tire eaters there. Alternately you go with the Conti Gatorskin but you may find those just OK not superb.