I think what I said still covers it, with the addition of a children's category. I dunno, I don't frequent regular stores very often, and when I do the book section is a place I tend to avoid. But if I remember correctly there are children's books, and the standard cooking/politics/how-to books that are so popular on amazon's bestseller list. They probably wouldn't have the specific popular books like Hunger Games and whatnot, however.

But like I said, ordinary stores are the last place I'd look for books, and I wouldn't buy them from there unless I spotted something spectacular. For the most part it's just really mediocre (at best) stuff, and at worst garbage. And if that's what you meant by mainstream then my opinion of mainstream is even worse than I previously suspected.