Flying into LAX at 8:30 on a Friday morning, and out at 11:00 a.m. on a Monday. Should we hop on 405 up to 10 and over to 1 or is it better to take 1 all the way?
You would take Lincoln to the 10, which turns into Pacific Coast Highway. That's the only route to take.
Lincoln Blvd. is also Route 1, which is also Pacific Coast Highway. Stay on Lincoln the entire way to Santa Monica, where, at Lincoln/Olympic, you will follow signs for Pacific Coast Highway (a left turn).
Did you book a place in Malibu? If not, Santa Monica is your best bet.