Hello - We decided to take a Globus Tour which starts in SF, then Napa Valley, Lake Tahoe and winding down Big Sur and ending up in San Diego (12 days in all. We will be arriving on September 25th. What is acceptable to wear at that time of year? I hear SF is really chilly and we should dress in layers as we go down the coast. Are white slacks acceptable in Sept/Oct? Any suggestions? Thanks.