Hey Jon,
What part of K town are you coming from/what part of Santa Monica are you going to? I live in H wood, and the roads I prefer to take west are Olympic, Venice, Melrose, Beverly, or Wilshire, then turning onto Santa Monica Blvd. Beverly gets ugly for a few blocks through the country club, and Olympic can get hairy through Century City, then further into Santa Monica. I'd say Wilshire to Santa Monica is the best route.
Charleville - one street south of Wilshire- parallels Wilshire and is all 4 way stops and lights at major roads.