There are three main dialects of American English: New England dialect, Southern dialect, and General American dialect on the west coast. Ebonics should go in there too.
English accents are often categorized according to rhoticity:
Smectic Chaos
One notable feature of Californian English is the use of the vocal fry, which is a creaky or popping sound at the end of sentences or words. Another feature is the use of "like" as a filler word or discourse marker. Californian English also tends to have a more relaxed and laid-back intonation pattern compared to other varieties of American English. That may be a result of the endless blue skies and beaches...
Most of America is rhotic, but there are some non-rhotic accents (like Cajun English, for example.)