These are some of the most enjoyable reads I've come across. Perhaps you'd like to try:
Stephen King's The Dark Tower Series. Seven books in all, not really 'horror' but more of a fantasy-action-suspense-western tale.
Daniel Keyes' Flowers for Algernon.
Umberto Eco's Foucault's Pendulum. I had to stop many times though, to look up its esoteric themes -- quite a lot but interesting to find out about.
Richard Matheson's Bid Time Return. It's a romance novel, but not thrashy. Somewhere In Time (the old movie) is based on this.
I think I can go on and on and on...