Together and apart, Pohl and Kornbluth were absolute masters of sharp, effective science fiction. Their wonderful collaborations include Gladiator-at-Law, which makes a great companion piece with The Space Merchants, only in this novel it's the lawyers who rule the world, with gladiatorial contests staged to please the masses.
Kornbluth's best solo novel is probably The Syndic, in which America is ruled by rival criminal gangs, although for most people daily life is pretty much unchanged so long as their protection money is paid on time.
Pohl's solo novels include Man Plus, which won the Nebula Award. It's the story of a man being altered to allow him to survive on Mars, but the more he is changed the more distant he becomes from his human self. However, Pohl's very best novel is our Alternative Choice.
Gateway, which won the Hugo, Nebula, Locus and John W. Campbell Memorial Awards, is one of those fascinating novels, like Arthur C. Clarke's Rendezvous with Rama, which explores the alien without any aliens actually appearing. Gateway is a space station built by a long-vanished race, the Heechee. There are hundreds of alien craft abandoned around Gateway, but humans have no idea how to operate them. Slowly, by trial and error, they learn to master some of the controls, but the results can still be disastrous. The novel tells the story of one volunteer who becomes phenomenally rich as a result of his mission, but only at the cost of his friends and colleagues being sent into a black hole. Gateway was the first of the Heechee novels, with five other books following, but like the Rama novels the series becomes far less interesting once the actual aliens put in an appearance.