We usually take I-5 to 126 to 101. Just an easier drive, less traffic. There is a grade on 101 south of Paso but far shorter than I-5/Grapevine.
I-5 is ok, but yes can get snow usually at night, early morning. Very rare during the afternoon. Highway 46 from I-5 to Paso is very good easy drive.
We drive from Phoenix to Paso once a year. Love the area, lots of great wineries and restaurants. Lately we've been avoiding most of the L.A. area entirely by taking I-15 to 395 and over thru Tehachapi to 99 and over to 5. It to can get snow in a bad storm but so far we've never had that happen.
