DD has plenty of challenging books in her room at her reading level, she just doesn't pick them up. She often chooses books that are below her actual grade level. Whether it's laziness, or lack of self-confidence, I don't know. I've threatened to take all the books out of her room that are below her level so that she tries the more advanced ones. I sound like a horrible pushy hothousing parent but that is what I'm dealing with. Lazy gifted children. DS, my younger kid, is even worse and has been able to read chapter book for a couple years (and can read them in about 20 minutes) but every time I suggest one he whines and says that they are way too long. He had a teacher last year in Kindergarten who made him read Beverly Cleary books like the Mouse and the Motorcycle and that was probably a very good thing for him. I don't do that at home--it's not worth getting into a battle.
Now this year in first grade he is actually going backwards in school with his reading because the teacher is giving him stuff below his level. He is bringing home picture books with 5 words on each page.