When you say "LAX", are you actually coming from the airport itself, or do you mean the general Westchester/Culver City area? If you're coming up to the Valley from that area, you might as well stick to Sepulveda as that's the only "practical" way to get to Encino over the Santa Monica Mtns; you'd do better to check some of the nearby parallel streets that aren't as heavily traveled, like Bundy or Barrington. If you don't mind some extra mileage, you could go up the bike path along the beach, and head inland to Sepulveda from Santa Monica on one of the secondary streets (meaning, don't use Wilshire, Santa Monica, Pico...).
If you're actually coming from the airport, just throw the bike on a Flyaway bus and go up to Van Nuys, then ride down Woodley and Hayvenhurst to get to Encino. I know that sounds like taking the easy way out, but I'd rather do that than deal with Westside traffic.