In between reading "To Your Scattered Bodies Go" and "The Fabulous Riverboat" by Philip José Farmer, I took a brief detour and read "Riverworld and Other Stories", which contains the original novella on which the Riverworld series is based.
I would recommend reading the Riverworld novella after "To Your Scattered Bodies Go". As a reader, it's a lot easier to digest the background concepts if you're reading about them as a character experiences them for the first time. In the novella, we join the characters some years after the initial resurrection, without a lot of clear exposition up front. Without having read them, I think of the novella as a beta version of the fifth and six novels, which cover side trips outside the main arc of the Riverworld storyline.
Although the Riverworld novella is the highlight of the collection, there are other entertaining moments. I was surprised to learn that "The Henry Miller Dawn Patrol" was first published in Playboy, and yet "J. C. on the Dude Ranch" was not. Both are fun and raunchy stories, and wouldn't be out of place a few pages away from a centerfold. "The Problem of the Sore Bridge" was also a fun one for anyone who's a fan of Arthur Conan Doyle with a lot more humor and a dash of Lovecraft thrown in for good measure.
In short, if you can find a copy of the collection, pick it up, but read the novella at least after "To Your Scattered Bodies Go".
(If you want more information about Philip José Farmer and his work, I'd suggest taking a look at www.pjfarmer.com.)