I have always found it interesting (and usually kind of silly) that we separate genres into age groups. I understand the purpose behind this - we have different experiences at different times of our lives. The average five-year-old would struggle to identify with a book about a thirty-year-old's life. They're just not there yet. It doesn't matter to them as much as books about games and bedtime and other things they actually worry about. Another obvious reason is reading levels, because we need beginner books unless we'd like to overwhelm kids and make them frustrated with reading from the very beginning - they wouldn't see the fun and likely wouldn't like books at all in the end.
But I think the silly part is that people are so strict about these genres and the ages at which others read them. I'm sure every YA reader has seen at least one of the many discussions out there about older readers and why they should/shouldn't be reading about teenagers. And I also think that many people put children's books, no matter how well-written, below their standards for what they would ever read.
Personally, I don't stray much into children's fiction. Too much of it doesn't interest me and so, although I'll read a few books now and then, it's not a normal thing for me. I also don't go any lower than middle grade reading - while I know there are great authors for small children out there, it's just not usually my style. I like words and going so far as picture books doesn't suit me. Even graphic novels aren't usually my thing, so while this does have a lot to do with reading level and my wanting more than ten words a page, it's also a preference of mine that goes further than that.
I have (fairly recently) noticed that I enjoy older children's books, as well. Most classics I enjoy are about children and intended for them to read, and I think they tend to be more suited for older readers as well as younger. I'd guess it's the reason they stuck around long enough to be classics, really.
But my main reason for this post is that I'm super interested in how others read when it comes to children's books. How low do you read in terms of age groups? What's the last book you've read that's lower than YA, if any?