I've always thought that in an ideal world, we would all have three hours in the middle of the day to do nothing except read. If such a thing ever comes to pass, here are a few of my favourite books you might want to put on your pile.
Speculative Fiction
Isaac Asimov, The Foundation novels, the Robot novels... okay, just about anything
Daniel Abraham, The Dragon's Path, The King's Blood
Carol Berg, Song of the Beast, Transformation
Carey, Mike, Linda and Louise, The Steel Seraglio
Gail Garriger, Soulless
David Eddings, The Belgariad
Steven Gould, Jumper
Barbara Hambly, The Darwath Trilogy, The Sun Wolf and Starhawk novels
Cynthia Hand, Brodie Ashton, Jodi Meadows, My Lady Jane
Frank Herbert, Dune
Nina Kiriki Hoffman, A Fistful of Sky
Alex E. Harrow, The Ten Thousand Doors of January
Katherine Kerr, The Deverry novels
Fonda Lee, Jade City
George R. R. Martin, Game of Thrones
A. Lee Martinez, Divine Misfortune
Anne McCaffrey, The Dragonriders of Pern series, The Crystal Singer trilogy
Vonda McIntyre, Dreamsnake
Patricia McKillip, Riddle of the Stars
Naomi Novik, The Temeraire novels
Sarah Prineas, The Magic Thief
Jennifer Roberson, The Sword Dancer series, Chronicles of the Cheysuli
Brandon Sanderson, Elantris, The Mistborn Trilogy
John Scalzi, Old Man's War, Ghost Brigades, The Lost Colony, Zoe's Tale
Sharon Shinn, absolutely everything, but especially Archangel
Robert Silverberg, Lord Valentine¹s Castle, Majipoor Chronicles, and Valentine Pontifex
Maria V. Snyder, Poison Study
Sabaa Tahir, An Ember in the Ashes
Laini Taylor, Daughter of Smoke and Bone Saga
Craig Russell, Black Bottle Man
Mary Stewart, The Merlin novels
Joan Vinge, The Snow Queen Cycle
Martha Wells, The Murderbot Diaries
Terri Windling, The Wood Wife
Chris Wooding, Tales of the Ketty Jay
J.R.R. Tolkien, The Hobbit and The Lord of the Rings.
Mystery
Rudolfo Anaya, Zia Summer
Gail Bowen, the Joanne Kilbourne novels
Christopher Brookmyre, One Fine Day in the Middle of the Night
Lindsey Davis, the Falco novels
Janet Evanovich, the Stephanie Plum novels
Elizabeth George, the Inspector Lynley and Barbara Havers series
Catherine Hunter, In the First Early Days of My Death
Alexander McCall Smith, The Number One Ladies Detective Agency series
Elizabeth Peters, the Amelia Peabody novels
Peter Robinson, A Dry Season
Dana Stabenow, The Kate Shugak novels
Laurence Shames, The Naked Detective
Josephine Tey, Daughter of Time
Mary Willis Walker, Zero at the Bone
Non-fiction
Diane Ackerman, A Natural History of the Senses
Allan Chinen, Once Upon a Midlife
Richard Coniff, Spineless Wonders: Strange Tales from the Invertebrate World
Martha Crump, In Search of the Golden Frog
Donald Johanson & Maitland Edey, Lucy: The Beginnings of Humankind
Bill Laurance, Stinging Trees and Wait-a-whiles
Margaret Lowman, Life in the Treetops: Adventures of a Woman in Field Biology
Katherine Phillips, Tracking the Vanishing Frogs
Peter Lane Taylor, Science at the Extreme
David Quammen, The Song of the Dodo: Island Biogeography in an Age of Extinction
Daniel Quinn, Ishmael
Other Stuff
T.S. Eliot, Old Possum's Book of Practical Cats
Pauline Gedge, Child of the Morning
Betsy James, He Wakes Me
Barbara Kingsolver, Animal Dreams
Madeline Miller, Circe
Farley Mowat, Owls in the Family
Yuko Ota and Anath Hirsh, Lucky Penny
Jane Yolen, Owl Moon