In the interest of odor control, labor-saving, and economy, we have always used clumping litter in our multi-cat household, even with kittens. I have read recently that it's "bad" for cats but honestly we've never had any problems. Once they are all-raw I plan to investigate other more "natural" options but I'm in no rush.
"I love cats because I enjoy my home and, little by little, they become its visible soul."--Jean Cocteau