I take the opposite view.
We place so much stress on learning about "the culture" of the language we're teaching or learning. That's great, and it's important -- but what is the first thing most learners need to talk about, right from the start when they take out that pile of photos to show people in China? Their OWN culture. This is a picture of Christmas at my house, and this is how we celebrate. This is Hanukkah. How many Chinese textbooks mention Hanukkah, let alone give anyone the vocabulary needed to talk about it intelligently in Chinese?
So in terms of finding books to expand one's language capabilities -- I tend to recommend books translated into Chinese from English. For a learner, there is a great advantage in reading a book with which he is already familiar. Harry Potter is quite difficult in Chinese for most learners, but there are shorter works available, like the Magic Treehouse series and many other children's (not emergent reader) and adolescent fiction. Heck, get the Hunger Games in its Chinese version (probably another very difficult one since made-up words would not be marked clearly, but I digress.)
Get a book you're familiar with and would enjoy reading. Then use the advantage of knowing the cultural background, the characters, and maybe even the specific plot, to help you READ. Not decode. READ. All that language flowing into your brain and being understood will do a lot to advance your Chinese overall. Then you can use your improved abilities to read things where you don't have those advantages, like "authentic" materials (overrated, IMO, in their value to learners, but ultimately the goal toward which we are helping learners.)
The other thing that has revolutionized reading for this generation of Chinese learners is Pleco. The PlecoDic app for iDevices (and other platforms as well) includes a reader. If you can find the reading material in digital form (text), you can copy it into the reader and look up anything just by touching the screen. It can make the difference from a piece of literature being inaccessible to being something a learner could read without frustration, or with a lot less frustration.
The crucial thing for reading colloquial Chinese is to have a solid underpinning of spoken language that you understand immediately. Written Chinese of this type doesn't absolutely reproduce spoken language exactly but it's pretty close. If you need to stop and decode each word you're adding another step to the process (it becomes text > Chinese > meaning rather than text> Chinese=meaning) and you will find that the weight of the unknown words and phrases becomes greater since they are more disturbing to your overall comprehension process. If you can automatically parse and comprehend "normal" language, you will have more brain resources left over to mull over the meaning of unknown terms you encounter, rather than having the entire train of thought you've got going unceremoniously derailed by the first word you haven't seen before. (The way reading is taught in Chinese classes also needs a huge overhaul, as it emphasizes looking up each word rather than using reading strategies. But I digress.)