I would avoid the 210 and the 5 fwy, lots of traffic once you get closer to and in the Pasadena/L.A. general areas, even on weekends. The 40 and 58 is a much nicer drive. You'll get some hills on the 58 west of the 14, but not terrible or very long, and the scenery is beautiful there.
Last Spring, I drove from Phoenix to Barstow via I10 to 72 to Parker, to 95 to Needles and then west on I40. Both 72 and 95 are single lane roads but pretty traffic free, and I'm not thrilled with Interstates or heavy traffic and hit neither. Hint, gas up in Az because gas is about 30 cents cheaper than in California. Hint 2, If you have the time check out the little town of Kelso and Kelso dunes. I thought they were both worth the 21 mile detour and if you do, you can keep going north and meet up with I15. Road a little bumpy but paved. LOL
