Atherton: Now the nation’s most expensive zip codeHome prices are up all over the Bay Area, but nowhere are they more stratospheric than Atherton. Home prices in this wealthy enclave are up over 40% year over year– a figure all the more impressive when multi-million dollar transactions are the norm. The result? The Atherton zip code–94027– i via Sfgate USA’s Most Expensive Zip Code? #Atherton, CA in Silicon Valley...