Regarding California, it's complex. Some of the nicest cities are there, but some of the worst.
La Jolla, Belvedere/Marin County, Pacific Grove/Monterey, Palm Springs- lovely places.
I worked as a consultant with the California Dept. of Corrections, and got to visit all the awful places tucked away in the high desert and Central Valley.
From south to north: El Centro/Imperial County - close to Mexicali. Basically like a small Tijuana without the luxuries, such as paved roads. Forget a car, bring a burro.
Salton Sea- the stench will overwhelm you as you get within a few miles. Scary place both in the day and night. Angry people, angry dogs, and that stench. And more meth.
Coachella/Indio- Riverside County: see El Centro. More paved roads, but without the rural charm of El Centro. Also more meth and shanty towns with feral dogs and wind strewn trash. Summer temps of 110+, makes the feral dogs very irritable.
Barstow/Victorville-San Bernadino County. Ugly tract homes and trailer homes nestled in the barren wastelands of the high desert. Think Mad-Max dystopia, with meth.
Bakersfield- now we are heading north along the 5. Tijuana meets Appalachia, with more meth and dust. Roasting heat in summer, without the backyard pools of Palm Springs.
Fresno- a bigger Bakersfield, with increased dining options (Outback Steak, that chain with jungled theme junk- not Sambo's, Chili's). More gangs and crime and meth. Very violent cops here.
Stockton- smaller Fresno, with just as many gangs and more crime. Declared bankruptcy, maybe this is why there a less police. Very high unemployment rate, but does host the annual Asparagus Festival.
Along the coast, at the far north:Pelican Bay, home to the supermax prison full of the most violent felons. Everyone here is either custody staff (sociopathic in their own way) or families of the felons (and apples do fall close to the tree). Best to put your kids in private school as to avoid the budding sociopathic offspring of the inmates.
