You guys are awesome!! Look, here's a big list of all the great titles and series that you guys came up with. I tried to divide it loosely into genre but forgive me - some books really fall into more than one category, or defy category completely. There are just SO many great books out there - it's great to get tried and true recommendations. (I'll keep adding your suggestions to this list - could you, if you leave a comment with one or two, give me the author as well?)
Happy Reading!
Classics (or otherwise great) Mrs. Piggle-Wiggle series, by Betty Macdonald
Mary Poppins, by P.L. Travers
Ginger Pye, by Eleanor Estes
The Moffats
Just So Stories, by Rudyard Kipling
The Wind in the Willows, by Kenneth Grahame
The House on Pooh Corner, by A.A. Milne
The Wonderful Wizard of Oz series, by L. Frank Baum
Alice's Adventures in Wonderland, by Lewis Carroll
Peter Pan, by J.M. Barrie
Pippi Longstocking, by Astrid Lingren
Charlotte's Web, by E.B. White
Stuart Little
Trumpet of the Swan
Henry and Ribsy, by Beverly Cleary
The Mouse and the Motorcycle
Ramona series
The Penderwicks, by Jeanne Birdsall
The Penderwicks on Gardam Street
The Secret Garden, by Frances Hodson Burnett
A Little Princess
Little Women, by Louisa May Alcott
Little House in the Big Woods and series, by Laura Ingalls Wilder
Cheaper by the Dozen, by Frank B. Gilbreth, Ernestine Gilbreth Carey
Mandy, by Julie Andrews
Chitty Chitty Bang Bang, by Ian Fleming
Mr. Popper's Penguins, by Richard and Florence Atkins
The Little Prince, by Antoine de Saint-Exupery
The Cricket in Times Square, by George Selden
Where the Red Fern Grows, by Wilson Rawls
Summer of the Monkeys
Five Little Peppers and How they Grew, by Margaret Sidney
Harriet the Spy, by Louise Fitzhugh
Poppy, by Avi
The 13 Clocks, by James Thurber
Betsy-Tacy, by Maud Hart Lovelace
Shoes series, by Noel Streatfield
Shel Silverstein (poetry)
Lost Queen of Egypt, by Lucile Morrison
Recently WrittenRoxie and the Hooligans, by Phyllis Reynolds Naylor
The Evolution of Calpurnia Tate, by Jaqueline Kelly
Gone-Away Lake and Return to Gone-Away, by Elizabeth Enright
My Father's Dragon series, by Ruth Stiles Gannett
Clarice Bean series, by Lauren Child
Anything Louis Sachar
Anything Judith Viorst
MysteriesFrom the Mixed Up Files of Mrs. Basil E. Frankweiler, by E.L. Konigsburg
The Boxcar Children, by Gertrude Chandler Warner
Nancy Drew series, by Carolyn Keene
The Hardy Boys series, by Franklin W. Dixon
The American Girls Series
FantasyThe Chronicles of Narnia, by C.S. Lewis
Mrs. Frisby and the Rats of NIHM, by Robert C. O'Brien
The Book of Three and series, by Lloyd Alexander
The Giver, and series, by Lois Lowry
The Return of the Twelves, by Pauline Clarke
Five Children, by E. Nesbit
It, by E. Nesbit
Charlie and the Chocolate Factory, by Roald Dahl
James and the Giant Peach
The Twits
The Witches
Fantastic Mr. Fox
The BFG
Danny, Champion of the World
Matilda
The Phantom Tollbooth, by Norman Jester
The Spiderwick Chronicles, by Holly Black and Tony DiTerlizzi
The Princess Academy, by Shannon Hale
The Goose Girl (and series)
The Tale of Despereaux, by Kate DiCamillo
The Mysterious Journey of Edward Tulane
The Mysterious Benedict Society series, by Trenton Lee Stuart
Dragon Slipper Series, by Jessica Day George
Princess of the Midnight Ball
FunnyTales of a Fourth Grade Nothing, Judy Blume
Superfudge
Goosebumps Series, R.L. Stine
The Willoughbys, by Lois Lowry
Anastasia Krupnik series
Goonie Bird Greene
Historical FictionWhere the Mountain Meets the Moon, by Grace Lin
A Long Way from Chicago, Richard Peck
The Great Brain series, by John Dennis Fitzgerald
Magic Treehouse Books, by Mary Pope Osborne
Julie of the Wolves, by Jean Craighead George
The Wheel on the School, by Meindert deJong
Red Sails to Capri, by Ann Weil
Number the Stars, by Lois Lowry
For Older KidsHarry Potter series, J.K. Rowling
Artemis Fowl series, by Eoin Colfer
The View From Saturday, by E.L. Konigsburg
The Egypt Game, by Zilpha Keatley Snyder
Maniac Magee, by Jerry Spinelli
Stargirl
Frindle, by Andrew Clements
Nation, by Terry Pratchett
A Wrinkle in Time and series, by Madeline L'Engle
Anne of Green Gables series, by L.M. Montgomery
Emily of New Moon series
Dark is Rising series, by Susan Cooper
Percy Jackson series, by Rick Riordan
Chasing Vermeer, by Blue Balliett
Wright 3
The Calder Game
Great ReferencesHoney for a Child's Heart, by Gladys Hunt (book of book lists for children 0 - 18)
Birds & Trees Love of Books ListSarah Jane's list