California Highway One

Which way?

Northbound
Advantages: Some drivers experience a greater sense of safety here: you'll be on the inside lane of the highway with the inland cliff rising on your right and a lane between you and the drop-off to the ocean.
Disadvantages: The majority of pull-outs are on the ocean side of the road, meaning you'll need to cross over against traffic.

Southbound
Advantages: You'll have spectacular views, and easy pull-outs.
Disadvantages: Ever see Hitchcock's movie Vertigo?There'll be nothing between you and that 500 foot high view except thin air.

When?

This region of California has a Mediterranean climate: mild, but wet winters; dry, mild to hot summers.

Rainy Season
The rainy season lasts from November to April.

Advantages: Much less traffic—you'll frequently feel like you have the road to yourself. And less fog: on a clear day, you'll swear you can make out Hawaii on the horizon.
Disadvantages: Washouts are frequent during this time, meaning you may need to make detours, or abandon the trip entirely. Check with CalTranson road conditions.

Dry Season
Advantages: Little fear of washouts and predictably dry weather.
Disadvantages: Heavy traffic, especially on weekends. The coast is more likely to be fog bound, obscuring views.