I just went down Hwy 395 in CA and had a great time. From Redding, you can take 44 over to Susanville, then get on 395. Visit Lassen Nat'l Park on the way.
On 395....from Carson City we did a day trip to Lake Tahoe. Further south there's Mono Lake, the east entrance to Yosemite, explore June Lake Loop, Mammoth Lakes, Devil's Postpile. Then there's Convict Lake, Ancient Bristlecone Pine Forest, Alabama Hills, Mt. Whitney portal. We stayed at Bishop RV Park (at the fairgrounds) and Boulder Creek RV Park near Lone Pine because we needed hookups. There are several non-hookup campgrounds just off 395.
When you reach Barstow, CA you can take I-40 east to AZ 95 south along the Colorado River. A couple State Parks and county park to stay at along there. Continue south to I-10 then into Phoenix.
This is just one way to go. Of course there are others.
