I just wanted to post the itinerary to our Californian road trip - I found it really helpful reading about other people's itineraries to help plan ours so wanted to pass forward the favour!
We travelled on a fairly tight budget, but the budget is mostly effected by the hotels you stay in so I won't comment on that here. We had two of us to drive. We flew in and out of LA, so this route is circular. You could probably start it at any point in the route, such as San Diego, San Francisco or Las Vegas. The total drive was around 2000 miles, fuel (at around $4.10 per gallon currently) cost around £200 / $300. We took 16 nights, but it would be easy enough to reduce it to 14 or 15.
1. Arrived in LA, picked up car; spent night here.
2. Drove to Pismo Beach along Hwy 1, stopping at Santa Barbara.
3. Spent day in Pismo Beach doing kayaking tour of coast (could equally be stoppover with activity in Santa Barbara or Monteray).
4. Drove up from Pismo Beach along Hwy 1 to San Francisco (Big Sur).
5. Spent day in San Francisco.
6. Spent most of day in San Francisco; drove 1 hour north to Sonoma in afternoon.
7. Sonoma wine valley for day.
8. Drove from Sonoma to Mariposa (gateway town to Yosemite).
9. Went to Yosemite and climbed a mountain; drove to Fresno at end of day (though any other gateway town would be just as good).
10. Day at Kings Canyon / Sequoia.
11. Drove via Sequoia or the Sequoia National Forest to Lone Pine.
12. Drove to Las Vegas through Death Valley, exploring the park on the way.
13. Day in Las Vegas.
14. Drove from Las Vegas to San Diego (a long day's drive).
15. Day in San Diego.
16. Drove back to LA to get flight home.
The whole trip was really well paced except possibly day 14 - another way of doing this would be to drive to Joshua Tree (just over half way) and stop around that area, then drive to San Diego / LA for a night.
I wouldn't have stayed in Fresno - somewhere closer to the parks or nicer would have been preferable.
Also, if you don't fancy Las Vegas (good for the spectacle, but I wouldn't go back), either take extra time in Yosemite / Sequoia or take more time doing the journey from LV to LA. There's plenty to do on the way, such as the Mojave Reserve, Joshua Tree NP, Palm Springs, San Diego...
And that was our road trip! A lot of time, the road was part of the adventure - in particular, Hwy 1, the roads around Sonoma and day 9-12 (the drive from Yosemite through to Death Valley).
I hope that the above helps other travellers planning road trips in California - feel free to ask any questions you have!