We take the 138 all the time coming back from Las Vegas. Good mostly 2 lane road, but it too can be congested. Take anything to the 210 west, as you get to Pasadena get in the right lane around Hill street exit and continue on the 210 west. If you miss this split just stay on the freeway a couple of exits to the 2 North, and take it to the 210. The 210 will merge with the 5 in San Fernando, and take the 5 North to Castaic. You will hit a few miles of heavy congestion at the 5-14 split, it is almost unavoidable, but once over the hill an in the Valencia area the traffic opens up. Happy Trails.