It would depend on if she were reading alone or with a parent. I know that sounds odd but if the parent and child read together (even if not at the same time) they can discuss nightly or weekly. Gives them a chance to bond. I love the classics. Charlottes Web is a good place to start at that age.
There's a children's illustrator named Graeme Base (you may already be familiar with him?) who does gorgeous work in picture books. The illustrations are more detailed and sophisticated, so a eight year old would still appreciate them. My favorite is his book "Animalia".
The best book to get your 8 year old is a girlie book if she's a girl. Ask her what kind if books she likes and when she tells you you, you will an idea. If it's a boy then ask the dad and he should know what to get him because boys have lots of things in common.