One advantage to going north->south is that you can look right down to the ocean with nothing blocking your view.
I rode this in July many years ago. Summer is fog season, whereas September & October usually have sunnier and warmer weather. I recall biking in and out of fog & sun, and I often had to stop to put my jacket on or take it off, because the temperature varied wildly.
A week is rushing it. Santa Cruz, Monterey/Carmel, the Big Sur coastline, Hearst Castle, San Luis Obispo, & Santa Barbara, are all worth a visit.