Consider renting a car for convenience as the attractions are scattered throughout Calabasas and Malibu. Rideshare services are also an option. Expect to spend around $120 for three days on car rentals and gas, and around 30 minutes to an hour for travel per attraction.
If you have more time, consider checking out the Getty Villa or spending another day at the beach. If you have less time, skip the hike at Malibu Creek State Park and the spa day at Four Seasons Westlake.
The nearest airport to Calabasas is Los Angeles International Airport (LAX) which is approximately 31 miles away. Van Nuys Airport (VNY) is another option and is approximately 13 miles away. Burbank Bob Hope Airport (BUR) is approximately 21 miles away.