I usually begin my read alouds with picture books and then move to a short easy novel before I start reading books that might be at or above my students' reading levels. Lots of my students haven't read all summer long, and I am modeling what they need to do to rebuild their fluency and stamina: start with lots of quick, easy reads to build confidence and refresh skills.
I just finished a great book for a first-week or early-in-the-year read aloud:
Monday with a Mad Genius (Magic Tree House #38)
by Mary Pope Osborne
It's the first day of school for Jack and Annie, and Jack is his typical worry-wart self. Luckily, time freezes in Frog Creek, PA when Jack and Annie travel with the magic tree house, because 10 minutes before the first day of school, they travel to Florence, Italy to meet Leonardo da Vinci and try to learn another secret of happiness to help Merlin.
At first, da Vinci tells Jack and Annie that the secret of happiness is fame. But by the end of the book, he has changed his thinking. He realizes that the secret to his happiness is curiosity.
Jack and Annie get back to Frog Creek at the moment they left, and they run to school filled with eager questions rather than nervous questions about the beginning of the school year.