I found a great list of books for summer reading from this site. On the lists are a recommended list of books for children from pre-K to high school to read for the summer.
Just a warning- it’s a pdf file. Sometimes they can take a long time to open. They won’t open if you don’t have Adobe reader on your computer.
At any rate, here it is: http://www3.caroline.k12.va.us/forms/sumrdlists.pdf