Do you have a little more detail about where you will meet in Westlake? That is where the 23 (called Westlake Blvd at this point) and the 101 meet.
I won't be able to drive down to Marina Del Rey (family and church commitments) but I should be able to swing by if you know where and roughly when on the upper end. I live nearby in Thousand Oaks.
Be careful on the 23 (Decker Canyon, part of Mulholland Highway, and part of Westlake Blvd). There are parts of it that are treacherous.
