Most of the material in these books is designed to put a bit of real-world depth into your games. III is pretty good as well for campaign building, though I have not used this book as often. Playing in a City of Greyhawk campaign where all of the characters were rogues, i looked to Canting Crew often as a source of inspiration for my character's speech, mannerisms, and daily life living in the shadows and allyways of the City of Hawks. I: Canting Crew has been extremely beneficial. When it comes to rogues, thieves, and such Vol. World Builder gives my campaign a more visceral touch to it, and I love it. The World Builder book just has so much information in it about everyday, mundane things that a GM might not think to include in his game.
