Not an exhaustive list by any means, just our favorites. I will add to it as we discover new favorites. The ages are just the ages that we read them at, and are not necessarily hard-and-fast. Most really good literature can be enjoyed by young and old alike.
Board Books and other Toddler Favorites
The Runaway Bunny by Margaret Wise Brown
Guess How Much I Love You by Sam McBratney
Brown Bear, Brown Bear What Do you See? by Bill Martin Jr and Eric Carle
Little Cloud by Eric Carle
The Carrot Seed by Ruth Krauss
Goodnight Moon by Margaret Wise Brown
Freight Train and Inside Freight Train by Donald Crews
Good Night Gorilla by Peggy Rathman
The Very Hungry Caterpillar by Eric Carle
The Little Drummer Boy by Ezra Jack Keats
Eloise Wilkin Stories (affectionately known as "Babies" around here)
Richard Scarry's Best Storybook Ever!
Shorter, Simpler Picture Books
Caps for Sale by Esphyr Slobodkina
Corduroy and A Pocket for Corduroy by Don Freeman
Harry the Dirty Dog and the other books about Harry by Gene Zion
Harold and the Purple Crayon and others in the Harold series by Crockett Johnson
Angus and the Ducks, Angus and the Cat, and Angus Lost by Marjorie Flack
The Snowy Day, Whistle for Willie, Jennie's Hat and others by Ezra Jack Keats
Blueberries for Sal by Robert McCloskey
Make Way for Ducklings by Robert McCloskey
All About Alfie and others by Shirley Hughes
The Story about Ping by Marjorie Flack
Madeline and others in the series by Ludwig Bemelmens
Pancakes, Pancakes, The Grouchy Ladybug and other by Eric Carle
The Mick Inkpen Collection (Kipper, Billy's Beetle, and The Blue Balloon are our favorites from this collection)
Dr Seuss' ABC by Dr Seuss (we save the other "I Can Read" type Dr Seuss books for early readers to read on their own)
If You Give a Mouse a Cookie and others by Laura Joffe Numeroff
Millions of Cats by Wanda Gag
Longer, More Complex Picture Books
Mike Mulligan and His Steam Shovel by Virginia Lee Burton
The Little House by Virginia Lee Burton
Katy and the Big Snow by Virginia Lee Burton
Lentil by Robert McCloskey
One Morning in Maine by Robert McCloskey
Time of Wonder by Robert McCloskey
Burt Dow, Deep Water Man by Robert McCloskey
A New Coat for Anna by Harriet Ziefert
The Tale of Peter Rabbit and others by Beatrix Potter
Anatole and others in the series by Eve Titus
Bread and Jam for Frances and others in the series by Russell Hoban
any of the Original Curious George books by HA Rey (but be careful, there are a lot of knock-off ones that were published later based on the TV series that are NOT as good.)
Katie Meets the Impressionists and others in the series by James Mayhew
Thy Friend Obadiah and others in the series by Brinton Turkle
Flicka, Ricka, and Dicka series by Maj Lindman
Snipp, Snapp, and Snurr series by Maj Lindman
Cloudy with a Chance of Meatballs by Judi Barrett
any of the Original Thomas the Train stories by Rev. W. Awdry (as with Curious George, be careful and watch out for the originals, not those based off the cartoon series)
The Lightlings and other children's picture books by RC Sproul
The Little Lights series by Catherine Mackenzie (Christian hero biographies in simple picture book form)
St George and the Dragon by Margaret Hodges
The Kitchen Knight by Margaret Hodges
Chanticleer and the Fox by Barbara Cooney
The Complete Brambly Hedge by Jill Barklem
Tin Lizzie by Peter Spier
Horton Hears a Who, Bartholomew and the Oobleck and other longer stories by Dr Seuss
Capyboppy by Bill Peet
The Glorious Flight by Alice Provenson
Read Aloud Literature Particularly Enjoyed by my 4-6 Year Olds
Winnie the Pooh and The House at Pooh Corner by AA Milne
Milly Molly Mandy and More Milly Molly Mandy by Joyce Lankester Brisley
Thornton Burgess' Bedtime Stories (as well as his many other animal stories)
My Father's Dragon series by Ruth Stiles Gannet
The Little House on the Prairie Series by Laura Ingalls Wilder
A Bear Called Paddington and others in the series by Michael Bond
the Ramona series and others by Beverly Cleary
The Betsy-Tacy Treasury by Maud Hart Lovelace
Mr Popper's Penguins by Richard and Florence Atwater
The Wizard of Oz by L. Frank Baum
Charlotte's Web by EB White
Read-Aloud Literature Particularly Enjoyed by a 7-9 Year Old
(with listeners-in aged 4-6!)
Heidi by Johanna Spyri
A Little Princess by Frances Hodgsen Burnett
Various books by Patricia St John (My personal favorite is Star of Light, but they are all good!)
Homer Price and Centerburg Tales by Robert McCloskey
The Trumpet of the Swan by EB White
Ginger Pye and Pinky Pye by Eleanor Estes
Charlie and the Chocolate Factory by Roald Dahl
Brighty of the Grand Canyon by Marguerite Henry
Because of Winn Dixie by Kate di Camillo
The Door in the Wall by Marguerite de Angeli
The Five Children and It by Edith Nesbit
The Wonder Book and Tanglewood Tales by Nathaniel Hawthorne
Along Came a Dog by Meindert de Jong
The Chronicles of Narnia by CS Lewis
The Wheel on the School by Meindert de Jong
Dangerous Journey by Hunkin and Little Pilgrim's Progress by Taylor (both are children's adaptations of Bunyan's Pilgrim's Progress)
Cameron Townsend: Good News in Every Language (Benge) and other Christian hero books in this series
Simonetta Carr's Christian history picture book biographies
Read-Aloud Literature Particularly Enjoyed by a 9-10 Year Old
(With listeners-in aged 5-7!)
The Little White Horse by Elizabeth Goudge
Otto of the Silver Hand by Howard Pyle
The Story of the Treasure Seekers by Edith Nesbit
A Tree for Peter by Kate Seredy
The Green Ember by SD Smith (we listened on audio)
Swallows and Amazons by Arthur Ransome (we listened on audio)
Sources for Good Read Alouds
Some of my favorite sources to consult when looking for good, age-appropriate read-alouds:
Simply Charlotte Mason Early Years Read-Aloud List and Literature Modules
Sonlight Read Alouds
Charlotte Mason Help
Ambleside Online Free Reading Lists
The 1000 Good Books List