So, maybe we could say that the Genus Loci of the place was twisted by the building of a hotel on a pristine spot and now blindly seeks powers? Call it a small one, a wannabe when compared to Demonreach, but something like that.
...
Whatever it is, the Being is now tied to the hotel and can affect its grounds. It calls itself calls itself 'The Manager' - and it sometimes refers to itself as 'we'. It can project power up to ten miles away, and when talking to vulnerable mortals the hotel implies that the echoes and ghosts that are part of it are "immortal" (so it can offer immortality). Its wants and needs seem simple enough - it wants psyche (or magical) energy to feed on and become stronger.
This is closest to what I was thinking... A Genus Loci, or something similar, that's been a little bit twisted and is slowly gathering power by feeding off of psychic/magical energy and/or feelings of terror. I want it to work subtly in the background, building unease and paranoia in its victims.
Aspects will fulfill most of that... But I could also give a few skills and powers to actively "attack" residents. Things like Domination (in the end, Delbert Grady had become a Renfield?), Incite Emotion, Glamours or Greater Glamours, Demense (What if the Hotel is a spot where the mortal world and the NeverNever are hopelessly mingled?), and so on.
Oh, reading the novel, I also realized... Take a look at the dates:
Ullman said: "The Overlook was built in the years 1907 to 1909. The closest town is Sidewinder, forty miles east of here over roads that are closed from sometime in late October or November until sometime in April. A man named Robert Townley Watson built it, the grandfather of our present maintenance man. Vanderbilts have stayed here, and Rockefellers, and Astors, and Du Ponts. Four Presidents have stayed in the Presidential Suite, Wilson, Harding, Roosevelt, and Nixon."
"I wouldn't be too proud of Harding and Nixon," Jack murmured.
Ullman frowned but went on regardless. "It proved too much for Mr. Watson, and he sold the hotel in 1915. It was sold again in 1922, in 1929, in 1936. It stood vacant until the end of World War II, when it was purchased and completely renovated by Horace Derwent, millionaire inventor, pilot, film producer, and entrepreneur."
Every seven years, something happens to make the owners sell the Hotel. Built in 1907, then... 1914, 1921 (Remember the photo of Jack at the 1921 July 4th ball at the end of the movie?), 1928, 1935, it's shut down during WWII but Derwent buys it in the early 40's (1942-43?) reopens it in 1945 and sells it after losing 3 million dollars on it, then a gap in the history, Shockley buys the Hotel in 1970 (Delbert Grady!), 1977 (King writes the novel, and Torrance goes nuts!). Since then, that gives us 1984, 1991, 1998, 2005, and finally 2012 (Next year!). Spiritual growth rings?