Jean Fritz books also The Story Of... biographies by Margaret Davidson and others
Tornado by Betsy Byars
The Iron Giant by Ted Hughes
The Littles
The Bears on Hemlock Mountain and
The Courage of Sarah Noble by Alice Dalgliesh
How to train your Dragon by Cressida Cowell
The Bone series by Jeff Smith
Tales from the House of Bunnicula series by James Howe
Lulu and the Brontosaurus by Judith Viorst
Mrs. Piggle Wiggle
Definitely Mrs. Piggle Wiggle. I just wish the print were not so small. I worry about DD's eyes.
These are mostly "o" level (mid third grade) books because DD has not read anything much higher than that. She also really likes books with historical elements in it.
DD is also in love with The Boxcar Children and Pippi at the moment as well as Cleary which are also "o". She will read anything by Cleary but is not quite ready for Dahl (at least not completely independent I think.)
What about The Neverending Story? Is that too hard? In my opinion Cricket in Times Square and Mr. Popper's Penguins are pretty boring. It sounds like your DS likes the more exciting stories. DD was fine with the Hobbit. I also think DD is trying to memorize D'Aulaires' Book of Greek Mythology.