I Let You Go by Clare Mackintosh. It was good and has one of those “NO FUDGING WAY!” parts midway through.

It's crazy because I know it's a very popular book, but the majority of the people I meet have never read The Hitchhiker's Guide to the Galaxy.

How else can they know the answer to life, the world and everything?

Right? Like... they must not be hoopy froods at all. :D

The Tenant of Wildfell Hall by Anne Bronte. A lot of people have read Jane Eyre and/or Wuthering Heights but not Anne's book. And up until last year I hadn't either, I was barely even aware of it. After I read it I couldn't believe more people hadn't, it is so good.

Castaways of the Flying Dutchman by Brian Jacques. Everyone knows Redwall, but this is my favorite book by him. It totally took me by surprise and I stayed up reading it all night. :D

Now I want to read it again. <3

I was going through my favorites on Goodreads and was dumbfounded that Getting to Know You by David Marusek (https://www.goodreads.com/book/show/1521606.Getting_to_Know_You) only had 168 ratings on GR. :-\ It's a great sci-fi story collection.

Honorable Mentions:
The Far Time Incident (The Incident Series #1) by Neve Maslakovic (https://www.goodreads.com/book/show/16163629-the-far-time-incident) (if you like time-travel, it's currently free on Kindle Unlimited)
Missing Reels by Farran Smith Nehme (https://www.goodreads.com/book/show/20893614-missing-reels) (written by a serious film buff; it was an intriguing mystery...can't remember if the film in the book is an actual lost film or not)
In Pursuit of the Green Lion (Margaret of Ashbury #2) by Judith Merkle Riley (https://www.goodreads.com/book/show/120633.In_Pursuit_of_the_Green_Lion) (I read this book first, not knowing it was part of a series, but it's still my favorite of the three. It's pretty hilarious, as well. Wish Merkle Riley had been able to write more books before her death. ;__; I am an absolute sucker for historians who write fiction.)
The Shambling Guide to New York City (The Shambling Guides #1) by Mur Lafferty (https://www.goodreads.com/book/show/15790895-the-shambling-guide-to-new-york-city) (I am including this for selfish reasons, b/c the publisher cancelled the series after 2 books, and Mur was going to self-publish the rest of her ideas when she had time to write them. I imagine book sales, etc. would help! It's just a great "kitchen sink" fantasy, and I always love those.)

Italo Calvino's books need more love!!

Man, these are some tough questions. I need to think about this one, too.