I prefer my stories taking place in L.A. because that's where I live. It always tickles me when a review mentions I managed to bring the surroundings alive. L.A. has so many different facets—it's one of the things I love about it.
Even when I use a location I know already, I like to take a refresher trip. It may bring forth a forgotten detail or I get to experience what it's like walking barefoot on dry underbrush (not pleasant). Most of all, it's a good excuse for an outing.
The other day I took a trip to the Angeles National Forest. I needed a spot where my heroes could discover a body. I could've just winged it, I've been through that area before, but I wanted to take another trip. I didn't regret it.
There are mountains, forests, national parks all over this town. It has always struck me how easy it would be to lose a body in them. Yeah, I know, morbid, but I like mysteries. And it does happen. For example, I found a news article about hikers who found humans skeleton unearthed by a brush fire.
I found my spot along an empty campground. It was a quaint place, with a tiny stream running through. The hillsides are dry as a tinderbox at this time of year, but the trees and shrubbery along the stream bed were green. Hiking trails ran off in different directions. Perfect place for a fictional shallow grave.