As of right DD has a TON of books but we're always on the lookout for more.

Anyways, pretty much all her books are some sort of story book. There's a clear story line, etc. We do have some non-fiction books that are directly related to some of her major interests too (like a butterfly book, for example).
But I know she's interested in reading, she's always pointing to words and asking what they are. She's got some sight words too and purposely looks through books that she has that has the sight words in them just to see them. I don't want to actively teach her but I do feel that it is important to give her whatever materials that she would want (ok, within reason.. I'm sure she'd love for me to buy a pool and build a playground just for her but that's not going to happen!).
We always try to encourage her interests, so I'm wondering if we should pick up some early reader books, like the Bob books? What did other parents do? Obviously, we'll continue to read a lot to her and she always sees my nose stuck in a book but I just wonder if I should try some of these books or not?