This is part 2 of my entirely opinion based series on where to live in LA.
Malibu/Santa Monica Mountains: Beautiful area, but a long drive to do anything with very few major roads in or out. There is also not a lot of commerce here, so unless you land one of the lucky few jobs or work from home, you'll spend more waking hours on the road than enjoying your home.
San Fernando Valley: This area is a collection of many different communities with widely varying characteristics. What they share in common is much hotter summers and sprawling one-story suburbs. There is a lot of work if you are in the film industry or an industry that is an accessory to the film industry. Otherwise you will likely have to go over the hills into the city proper which can only be done via 3 freeway passes or the one subway line.
Angeles National Forest: It sounds pretty cool to live in a national forest and you do have the amazing benefit of countless miles of trails at your doorstep. The mountains are truly beautiful. However, there is absolutely nowhere to work so you are stuck with frightfully long commutes.
Pasadena: Unlike it's smelly Texas counterpart, this is a pleasant city with a long history. There are many great old buildings, the scenic CalTech campus, lots to do, and ample employers. It is also connected to the city proper via light rail. There's not much separating this from a yes other than a bit less diversity and connectivity than the solid yeses.
Beverly Hills: If you are wealthy and enjoy sequestering yourself on your enormous suburban lot, this is the place for you. However, if you like reasonable prices and interacting with people who don't attend cocktail parties, this might not be your best bet.
Coastal Cities: You can't beat having the mighty Pacific Ocean as a neighbor (especially in an area with minimal tsunami and next to no hurricane risk). You do pay a premium for proximity. You also are stuck with a bit of a drive to get back towards town and the first 3 miles leaving the coastal cities is often ridiculously slow.