I will be taking a cruise out of San Francisco down to the Mexican Riviera and back again (10 day) and I'm wondering how to pack. How many days will be "cold" days and how many "hot"? I'm thinking that from San Francisco to San Diego I will need to pack sweaters if I want to go on deck? Of course..once we get to Mexico it will be summer..so I guess my luggage will be a two season one..I just hope I won't overpack because of it!! Does anyone have any suggestions?