I'm guessing it's best in the Summer when you can really enjoy the beaches
This is a great drive. Now, above I mentioned that to make the most of it you should probably travel in Summer, BUT it's probably packed with tourists in summer. Perhaps try to go a bit off season. Of course, it all depends on what you're looking for. If you want to play in the water. Go when it's warm. If you just want to sight see and you don't want to deal with bundles of traffic head out during non-peak season. This will also aid in reserving a hotel room or campsite as well.
Also, be warned camping is EXPENSIVE at any of the State Parks along the route. I didn't find anything less than $35/night, and for me, I'd rather sleep in my car parked somewhere inconspicuously.
Even if you weren't planning on making many stops, I am sure that the waves, rocks, surfers, beaches, and sunsets will have you pulling over numerous times over the course of the 130 miles of Pacific Coast Highway. It's great, just drive safely. People are maniacs out there, and you don't want to go driving yourself off of a cliff.