California is a state with natural beauty that stretches the entirety of the state to each of its borders. It is also a state where the beauty above ground in some areas pales with the beauty below ground. Like a sunset on an unknown beach, each of these areas offer solitude, otherworldly beauty, and in some cases, some of the most unique terrain on the planet. Even if you've never explored a cave before, each of these spots will interest and intrigue you, and provide you a great introduction to the world below your feet.
To put it in wilderness terms, the end of the year is a time to check your bearings, and see where you’re headed by scanning the horizon; or to use another tired cliché, view the entire forest, and not just the individual trees. That, I think is the nature of the holiday season: seeing what you are grateful for in your life; appreciating such people (or things that you are grateful for); and finding out where you will want to go (and perhaps how those people will help you get there).