I cannot recommend strongly enough a trip to Muir Woods north of San Francisco. Go early and you can enter before they officially open. I was fortunate enough to be alone there for some hours a couple of years ago when I visited. Talk about spiritual experiences – wandering around alone in Muir Woods is one of them.
“Everyone needs beauty … places to play in and pray in where nature may heal & cheer & give strength to the body & soul alike.” ~John Muir