If you like detective stories I can recommend you to reading "Poirot" by Agahta Christie. There are many shot storys and novels in this series that you can read them on the way to and from work.

Also I can recommend you a series books about Harry Potter. These books are wrote with simly words, and there are a lot of contemporary dialoges. Add that you can find audiobooks in this series, read and listen at the same time.

My favourite novel is Lolita by Vladimir Nabokov.

You can also try these other popular books:
1984 by George Orwell
Animal Farm by George Orwell
Fight Club by Chuck Paluhniuk
Of Mice and Men by John Steinbeck
The Talented Mr. Ripley by Patricia Highsmith
Fahrenheit 451 by Ray Bradbury
In Cold Blood by Truman Capote
The Great Gatsby by F. Scott Fitzgerald
Lord of the Flies by William Golding
American Psycho by Bret Easton Ellis
Far From the Madding Crowd by Thomas Hardy
Catch 22 by Joseph Heller
Perfume by Patrick Suskind
The Time Machine by H. G. Wells
The Invisible Man by H. g. Wells
We by Yevgeny Zamyatin

Otherwise, there are the classics by Charles Dickens, Jane Austen, Emily Bronte, etc. (But I think the books I mentioned above are much more interesting hehe!)

B2/C1 is a pretty good level so I'm sure you'll be able to handle these books with a bit of effort. It'll be good for learning new words and phrases too! :)

Hi my friend, you acctually can read some popular novels online, and most of them are not very difficult.  I have read several books like Time traveler's wife, The hunger game.... Game of Thrones is quite difficult for me. And I think the most important thing is you need be interested in the book you want to read, otherwise it will takes a long time to finish it. Good luck.