End of Sept/Beginning of October = Gorgeous on the central coast. When I was more involved in the wedding biz, we used to call it 'the new june'. Usually little to no fog on the coast and beautiful warm weather. And with the exception of Columbus day weekend, you largely have it to yourself - Have you been to Big Sur? A week might be a long time there, but it's a perfect 2 or 3 day adventure from Monterey/Carmel, or part of a road trip down to Santa Barbara. Yosemite is also beautiful that time of year, although it will be colder.
~ Dawn
Our little monkey (4/2011) & his early holiday present 12/12