Meaty and complex? I have an old trigonometry textbook you are free to have; I couldn’t put it down.
Most the meaty and complex books I have read tend to be political and I don’t want to tip my cap because a lot of whiny politicos may get their panties in a wad once they realize they are getting this passionate filthy yumminess from a “?”.
Nevertheless, I know you are a Brit but I highly recommend reading A People’s History of the United States from Howard Zinn, which covers the story of American history as told by the defeated, not the victors, which is left out of most American textbooks and likely all textbooks of our allied nations like the UK. No matter your political leanings, it’s eye opening to see this perspective.
If you are looking for a light read, I recently read Bridges of Madison County, and by the way the movie sucked and did not even tell the story in my opinion, so I recommend the book as well.
For a more complex fiction, can’t go wrong with 1984, Grapes of Wrath, or the Picture of Dorian Gray. Othello was my favorite from Shakespeare. I’m not one for most recent novels, to be honest. Michael Crichton was one I did read all his works though.
Hopefully there is something in there that will keep you busy while not looking at my smut.