I-80 on your timetable -- Or maybe the Gold Country is Cooler
To get over the Sierra Nevadas, you should plan on using I-80 and US-95 for the leg between San Francisco and Las Vegas. Even during the heaviest snow storms, they (mostly) keep I-80 open.
A really scenic route could entail exiting I-80 at Placerville and following the Gold Rush Trail <a href = "http://www.roadtripamerica.com/drives/ca49.htm">(CA-49)</a> through the foothills. There are some really fun bars and historical places along the route. When you reach Sonora -- head west and pick-up I-5 and jet down to Buttonwillow -- pick-up CA-58 to Bakersfield and on through Tehachapi and over to I-15 up to Las Vegas.
The road south from Las Vegas (I-15) crosses Route 66 several times -- on your way to San Diego.
questions about different CA trip
My husband and I will be in San Francisco for a few weeks for work and want to take 2 weekend excursions. One weekend we plan to go South along Route 1 and the other weekend we want to go inland. I'd like to go to Lake Tahoe and my husband would like to go to Yosemite. I'm wondering if we can do both in one weekend -- in particular, I'm not sure what the roads are like between the two, in terms of snow, or how long it would take. We don't want to spend the whole time in the car -- we'd like to at least do some short hikes here and there. So I'm wondering if we really should choose one or the other and not try to do both. Any ideas?