@versusreality the biggest recommendation I can give is that you start reading The Dark Tower as you go through the other books. The first book, The Gunslinger, is something you just kinda have to suffer through, but the rest is just incredible... and it sets up this crazy mythology with all of his other books. It's really his masterpiece.

Also, I'd probably say IT is my favorite horror novel. None of the movie adaptations really "get it" at all, and are sort of awful representations really, though the first part of the recent movie was a nifty thing.

If I were to throw out one more really earnest recommendation, Needful Things is incredible. It's also insanely dark, and one of the only books that's made me cry. As in, it really reduced me into a sobbing mess. It's amazing.