I pick the books for my son - if left to himself, he reads encyclopedias, Guinness book of records, Ripley's Believe it or Not, Lego catalogs etc for fun.
I pick a very eclectic mix of books and fill a bin and leave it around. I don't care about the reading level, just that there is a mix of genres and difficulty levels in there. He likes biographies and funny books the best. So, he reads far above his level in those categories. I think that there is no need for a reading level to pick out books - just get some from the library and see what clicks and what does not. That should give you a good starting point. I also sometimes ask the librarian at the public library to suggest reading material - I tell her what the latest books my son read were and based on that, she figures out what his level and interests are.
