For Intermediate-to-Advanced level, I would suggest straight-forward crime novels such as those written by Donald E. Westlake. They have enough complex words to deal with, but without using too many obscure/uncommon words and sentences.
If you feel the text in those is too easy, you can then try to move into more complex texts such as literary masterpieces, classics and certain types of adult fantasy/science-fiction which tend to be more difficult to read.
Tip: If you use Google search, type in the name of the book you're interested in and click on the "Books" -tab. You can usually find a preview of the book. See if you can read and understand the preview pages at the pace you are looking to be reading in, and then decide if you're interested in reading the whole book or not.
Reading and Listening are important when learning a language. Listening teaches you how to pronounce the words, how we use words in everyday speech, especially phrasal verbs, idioms and slang and how to understand the many different English accents.
Whatever you read, read because you want to read it and not because you think you should. Try to read a variety of writing styles. Read both fact and fiction. Read comics if you like comics. Also, read newspapers and listen to the news videos on the newspaper web pages, so you hear the accents. BBC.com & CNN.com are good places to start but there are hundreds of English newspapers online so find ones you like.
Also, I tell all my students about this site. Readlistenlearn.net It is free to use. It has stories and articles in different levels from elementary up to advanced. You can read and listen to the stories or articles. I always suggest reading out loud as you are practicing speaking and hearing yourself speak. There is also a vocabulary list with each one.
You can read The 7 Habits of highly effective people for Stephen Covey, It will help you a lot and start reading short novels.