I've never had a druthers to read the Big Novels. I've usually found them almost pointless. Which is probably more on me than any other thing. Always have preferred books with a bit of sparkle and imagination - great science fiction or fantasy - interesting in the worlds built and the characters in them. E.g., Jim Butcher and Seanan McGuire are nearly automatic buys right now.
As I've gotten older, my tolerance for blather has dropped like a stone, though. And some authors blather and yammer. E.g., a certain popular author lovingly details the military details of his space ships, which is really irrelevant to pretty much the entire rest of the book. Wish he'd keep that stuff in his private notefiles.
For non-fiction, I am, when I have the time, gripped by it to a great degree... although I confess I straight up fell asleep the other weekend.
I also note that my attention tends to wander a lot more than it used to when I'm bored. Some of this I attribute to the US national mood; some of it I attribute to Sturgeon's law and my increased sensitivity. And some of it I attribute to the dopamine hits social media gives us. I also wonder about experience and pattern matching - I'm 34, not 14. I've seen a fair bit of stuff before.
Another thing that I want to remark on - the non-fiction world is, simply put, a fascinating place that can be explored at will, to arbitrary depths, at this point. Fiction authors have to compete with, e.g., people on Twitter talking about their sessile spiny oysters and showing pictures of them off. If I was a hair less sleepy this morning, I might have spent 20 minutes learning about spiny oysters - where in 2004 I might have read a fiction paperback instead. So perhaps, in a certain subset of the population, we're all turning into the people who would have read the encyclopedia for fun, with its short articles on fascinating topics.