In the Jack London State Histork Park, the Wolf House ruins still remain. Jack had the elaborate house built, but it burned down before he was able to fully move into it. It's located in the rolling hills of wine country and Jack loved the farm life. Many of the farm structures still remain, including the ruines of a winery, barn, cottage, and even a smokehouse. The stone structures survived well, even if needing structural re-inforcements. The grave site is on a knoll overlooking the Wolfe House where Jack and his wife were burried. A lovely vineyard surrounds the property. It's only a short hike to get to the locations from the park entrance, but it does have some steep inclines.
If Jack's spirit were to be wandering around, this would be the location. He loved the wine country and his ranch, but died young (40) before he could fully enjoy it.
This would be a great location to reserve for a special evening ghost hunting event, but the costs are exceptional (several thousand dollars per area).
Given this is a public area with constant visitors, there's no real personal experiences. Seeing the ruins is haunting in itself, though. With the voice recorders, it sounded like there was a lot of faint whispers - most too faint to even list. This would be best to go at night without planes flying over and hikers around. I strongly think this place is haunted, but most of the voices were female; nothing really indicated that Jack London himself was still around.