Silicon Valley is two markets right now. In Santa Clara County, buyers have more options and more time than they did a year ago, and sellers are starting to feel it in their pricing. In San Mateo County, it’s the opposite. Fewer homes are coming to market, and buyers are competing harder for each one. Neither county has become a buyer’s market. But the advice I’d give a Santa Clara seller this fall is very different from what I’d tell one a few miles north in San Mateo. That difference is the story this month.