Did Stephen King ever write any Gothic books? If not, which of his books appeal most of all to Gothic-fans?

He certainly uses Gothic elements in his books, and some of his are 20th century examples of Gothic horror. "The Shining" and "Salem's Lot" are probably the most notable examples, especially in the way in which they are both obsessed with a spooky house/building, very much in the Gothic tradition.

I think BAG OF BONES and DUMA KEY are loaded with gothic elements. BAG OF BONES came out several years ago and DUMA KEY this year. They are my favorites of King although I am a true fan.