[calintexas]

California, while not as big as Texas, isn't compact. East into the Sierra's is much closer than west. Plus there are more choices and less traffic likely than what's available in the Coast Range and along the coast.

With the caveat that it's been many years since I've been on any of these roads: As long as it's a weekday and being after Labor Day even the main mountain highways should have fairly low traffic. 168 to Shaver Lake and on to Huntington Lake isn't bad. 41 into Yosemite Valley and then 140 back would be a lot of fun. Plus, Yosemite Valley is something to see if you haven't been there. 49 is good. 180 up into Kings Canyon and Sequoia National Parks is great. Plus there's lots of feeder roads. If you don't get specific feedback, put a loop together maximizing the squiggly lines that fits your time using Google Maps.

Update 9/24/10: I know the OP didn't end up needing advise, but in case someone else happens on this thread: 41 to Yosemite is heavily traveled even after labor day (and there are lots of people in the valley). Traffic on 140 is light, but there is a big slide that can mean a 20 minute delay (if you hit it wrong). 41 out of Morro Bay through Arroyo Grande to Shandon is quite good and lightly traveled on week days.