I own the book of The Shining, it's one of my favorites.
I actually thought Nicholson was perfect for the movie role. That's the problem with the movie, they didn't dive deep enough into the characters to get a good understanding of who they actually were beforehand. See, in the book, they hit on the main characters in a lot more depth, delving into the family dynamics and history, as well as the personal thoughts of each. Danny was actually Jack's stepson, but by watching the movie you would hardly know that. Also, I know the movie briefly mentioned this, but if you coughed or blinked you missed it, but Jack also broke Danny's arm a year or so before the story takes place, because Danny messed up some papers in his office or something like that. Jack was an emotionally and physically abusive, hotheaded, mental case from the get go, lol, and even in the movie, it was obvious that Danny and Wendy were both terrified of him, even before he got the seasonal gig at the Stanley. Oh, and the reason he needed the job at the Stanley was because he lost his previous job, though I can't exactly how, but I think he was fired and had been out of work for some time. I think it had to do with his terrible love of hard liquor, he had a major drinking problem. I do wish the movie had gotten more into that, but I guess there just really wasn't time for it. Bummer. Some stuff that they left out of the movie I was glad about, like the topiary shrubs that moved around outside. That was a little over the top for my taste. lol
ETA: Not to stray off topic, I am very interested in the new IT movie. It has to be better than the tv version 30 years ago. LOL