Any way you go will involve either PCH from the Malibu side, or Mulholland or Decker from the other side. I don't like the ride up PCH past Topanga (death alley?) so one could take bikes the 534
http://mta.net to Trancas or anywhere along the way past the sketchiest parts of PCH if you want to ride.. I think Charmlee is about 2/3 of the way to the "top" of the hill from PCH. The ride back down Mulholland past the Rock Store heading for Topanga is great too. I'd check gmaps for elevation info...