Chapter books are wonderful for literature circles whether you want to use them whole group or with leveled groups. Here are some of my favorites with links to my store to buy the unit plans. My prices are very reasonable.
A Charlotte’s Web Unit for 4th Grade – This is free!
A diversity unit using Walk Two Moons by Sharon Creech.
Literature Circle Task Sheets for Tuck Everlasting by Natalie Babbitt.