Philip José Farmer books in order
25 books in the catalogue, about 157 hours of reading in all; the shortest takes 3 hours and the longest 16 hours.
3 series and 17 standalone books in the catalogue.
Riverworld
5 books
World of Tiers
7 books 1 
The Maker of Universes 3.0 h 
A Private Cosmos 4.3 h
The Maker of Universes 3.0 h 2 The Gates of Creation length not known
4 A Private Cosmos 4.3 h 5 Behind the Walls of Terra length not known
5 The Lavalite World length not known
6 More Than Fire length not known
7 Red Orc's Rage length not known
Dayworld trilogy
3 books
Standalone books
Strange Relations 3.5 h 
The Hugo Winners 5.9 h 
The Hugo Winners, Volumes One and Two 15.6 h 
The World of Tiers 9.4 h 
Flesh 3.7 h 
Image of the Beast 5.1 h 
Tarzan Alive 6.0 h 
Venus on the Half-shell 3.7 h 
Thieves' World 5.2 h 
Microcosmic Tales 6.0 h 
Tales from the Vulgar Unicorn 5.5 h 
Sherlock Holmes Through Time and Space 6.5 h 
Amazing Stories 4.7 h 
Baker's Dozen -- 13 Short Science Fiction Novels 10.5 h 
The Mammoth Book of Vintage Science Fiction 9.2 h 
Alien Sex 5.3 h 
The Dark Heart of Time 7.3 h