I take it you will be taking Highway 5 no? I have always liked stopping in Manteca for a bite. Further up 5 you will pass Woodland, very rural farm labourer town with tackle and feed shops. Not an architectural gem, but it does give you a glimpse of its old western past. One place I LOVED there is Las Islitas Ostioneria, the kind of place you'd drive by especially as it abuts a dieing shopping mall with only a department store (JC Penny?) It's a large family restaurant specializing in seafood (yes, in Woodland) that is fresh. Huge bloody mary/beer type cocktails, and traditional Mexican music. Great atmosphere and very local. If you want something more upmarket, then take the wee detour of of 5 to Winters. Another great town, cute small downtown that has preserved the original buildings. Buckhorn on one corner and the wonderful Putah Creek Cafe opposite are good places to eat.
Redding is a funky town, with a few points of interest such as the river front historic park with a bridge designed by Calatrava (who knew?!) On weekends they have a cute farmers market.
Further up is Dunsmuir, a terrific old town, with a train museum (I think even a hotel with train cars as rooms), foothills, trails and volcano country. Great place to stay the night, but that would be a long day from LA and turn a three drive into 2!
If you are going to dip into Hwy 101 at all, Healdsburg and wine country are a nice place to consider a pit stop, Santa Rosa or Healdsburg. about 9 years ago