Our best hike was along the cliffs overlooking the ocean to a site where a large number of elephant seals were beached.
We parked at one of the parking lots off Hwy 1 and hopped the fence onto the national park land (our B&B host said it was okay to do this).
We hiked north along the tops of the cliffs, looking down at the waves, rocks, and occasional tide pools. We could hear sea lions barking as we hiked. Eventually we came to an area with some sand dunes and big rocks, overlooking the beaches where the elephant seal females and juveniles were basking. Most of the males were in the water, bellowing and bashing into each other -- very impressive to watch all that testosterone in action!
Note: don't get too close to these animals. The rule of thumb is, if they seem aware of you -- they look back at you, fidget, move, etc., you are too close.