Larry Niven & Jerry Pournelle, the Mote in God's Eye
Orson Scott Card, Pastwatch: The Redemption of Christopher Columbus
James Blish, Cities in Flight
Harlan Ellison, For I Have No Mouth And I Must Scream
John Brunner, Stand on Zanzibar
Roger Zelazny, The Doors of His Face, The Lamp of His Mouth
Harry Harrison, the Technicolor Time Machine, Make Room, Make Room, or any of the Stainless Steel Rat series. Or Bill, the Galactic Hero.
(I only name so many Harry Harrison novels because no one else does)
edit: Harry Harrison also does the rare trick of good comic science fiction.