I run a loop that goes from Westwood, down Olympic to Beverly, then down Beverly to Pico, Pico back to Westwood, and Westwood back to Olympic.
There are nice sidewalks the entire route and it's almost exactly 5 miles (4.95 mi). Even during high traffic times, there are only one or two places where you are usually forced to stop at lights, so it's pretty smooth. There's also some nice hill action when you get near the Fox plaza.
I'm all about running out my front door so I have 3 circular routes I do in my sunset junction area. All have variables hills (depending on how much of a challenge I feel like).
1. Run around Griffith Park blvd to West Silver Lake and then up the hills over Effie. Reverse works as well.
2. Run in narrower residential streets with less traffic towards Los Feliz blvd (crosss Los Feliz and run in the hills for a challenge)
3. Run on Hoover from Santa Monica towards Melrose and around the hills and towards Sunset then back to Santa Monica.
I love plotting new routes in Run Keeper. I've got a great 6-mile route down to the Rose Bowl and back into Old Town, and a 2-mile route right down Colorado, perfect for my Army Physical Fitness Test prep. You can find all my routes at http://runkeeper.com/user/jjcsforwood/route