Any book recommendations for a 9 year-old girl?

My daughter is a book addict. She reads all the time, including at the kitchen table, while brushing her teeth, and walking up and down stairs. After learning how to read at 4 years old, she burned through the entire kids’ section of picture books before moving on to more advanced “chapter” books at 5.

The problem is – she’s extremely bright and is often working on multiple books at the same time. There are books across the house with bookmarks at various points in the story. We can’t keep up with what she’s reading at this point. All I know is that she goes through a few books per week.

We also have had the opportunity to browse through some of these books and have found that some of them have rather “mature” themes. Now, I am far from one of those people who wants to protect her from reality, but I am hoping that there are some books that will meet her where she is intellectually and creatively, but not introduce a whole assortment of other themes just yet.

So, ideally, I think I’m looking for recommendations that meet some of the following:
– challenging enough (she’s in fourth grade, but in a special “advanced” reading group)
– a strong female protaganist
– unique
– fiction
– not focused on sexual or romantic relationships
– not overly-focused on death (enough of the “mom dies” stories)

Thanks!