You didn't say if you have boys or girls, so I'll give you some for both.
For girls:
Fancy Nancy books are a huge hit with my DD 7
Little House on the Prairie books, you can't ever go wrong with them
The American Girl books, my daughter particularly likes Felicity and Mollie
For boys:
The Boy at War series by Harry Mazar
Tales of a Fourth Grade Nothing by Judy Blume
The Encyclopedia Brown Books
The Guardians of Ga'Hoole books by Kathryn Lasky
My son loved The Tale of Despereaux by Kate DiCamillo
For either:
The Bobbsey Twins books by Laure Lee Hope
The Choose Your Own Adventure books by RA Montgomery, here they are given choices about where the plot can go and then after you choose you go on to see what happens with that option. It is fun because you can read the book more then once and have it be different then the first time.
The Chronicles of Narnia books.
By far my kids favorites are the Magic Treehouse Books by Mary Pope Osbourne

. They are wonderful because they're fun, but the kids are actually learning about history in the process

as Annie and Jack go back in time. We just had the opportunity to meet her at a book signing Thursday night and she used the kids to help her determine what her next book should be about. There isn't a child in our family who hasn't read and loved these books. Anyone out there whose kids love these books keep your eyes and ears peeled, as they have just turned Christmas in Camelot (minus the Christmas part) into a musical that will begin touring the country soon

.
My personal favorites are the Betsy Tacy books by Maud Hart Lovelace

. I love them so much I go back at least once a year and read them again. My first bad cold of the season

and I immediately turn to them to make me feel better. They're kind of like comfort food for the soul. They are I think more for girls, but my son when he was younger seemed to like them too. They start when Betsy and Tacy are 5 and continue on until they are married. They take place in the early 1900's and were written in the 40's and like the Little House books are based on the authors life. Anyone from Minnesota will get a real kick out of them

as they take place here and the town of Deep Valley is based on Mankato.
Have fun reading some of these new books with your kids.