Midwest Mom, Rick Riordan has another series besides Percy Jackson called the Kane Chronicles, which is about Egyptian rather than Greek mythology. It actually exists parallel to the Percy series (the Greeks live in Manhattan, while the Egyptian stuff happens in the Bronx I think?, but they mention that Manhattan is off limits, lol) I prefer Percy, but maybe if she started with these she might then be interested in moving to the Greek series. Also, there is the second Percy series as well which talks about the Roman vs Greek versions of the Gods.

As a child, I also really loved (still do!) the Harperhall series by Anne McCaffrey. Those are shorter books but get you into the whole Pern universe which is several dozen books. The Dragonflight series is good, too, but does have some sexual content.

And a friend's son is reading the Fablehaven series, which I had never heard of and am going to try to find. It has great reviews on Amazon. Maybe someone here is familiar with it?