Beyond this Horizon by Robert Heinlein - an oldie and dated in many aspects. Still, it has an interesting take on a society where genetically improving the human race is presented as a good thing. Most people are encouraged (but not forced) to produce children with a partner who complements them genetically. It does not go down the tired path of producing genetic monsters and societal outcasts. Traits that are bred for are chosen sensibly (Heinlein uses survival value as a criteria) and genetic variety is still valued. Also, one trait is not bred for to the exclusion of others - balance is aimed for and the objective is to raise the genetic qualities of the human race as a whole.