The Overman Culture, by Edmund Cooper
The House in November, by Keith Laumer
Re-birth (AKA The Chrysalids), by John Wyndham
Hawksbill Station, by Robert Silverberg
Children of the Star trilogy, by Sylvia Engdahl
The Changeling, by Zilpha Keatley Snyder
These are all wonderful books, though I seldom see them mentioned anymore.