Great news: The joyous-to-read Catherine Bigelow returns to SF Chronicle to observe the bizarre and intricate rituals of San Francisco society. (Bigelow used to be a full-timer at Chron, then went to 7x7, and now returns to the former as a freelancer. Whew.) Her first assignment? Sean Wilsey's stepmother's famous holiday party. "This year, Wilsey pruned her 350-person guest list a bit - mixing it up with faces from her other worlds: UCSF's Dr. Sam Hawgood, CEO Mark Laret and UCSF Chancellor Sue Desmond-Hellman, as well as politicos Attorney General Jerry Brown and Mayor Gavin Newsom, who've beelined to Wilsey's door (and pocketbook) for fundraisers," Bigelow notes in today's column. No word, however, if Dede unleashed her hounds on guests overstaying their welcome.