At yorkster's recomendation, I've been using World's Best Cat Litter for the past three months. Freckles (the cat) accepts it and I love it. I flush the feces and the clinging litter immediately drops away, so I know I could flush the urine clumps. too. They suggest changing completly every month, which I do. I (carefully)sniff tested month old litter and it smelled the same as when it came straight from the bag.
I noticed recent posts about stinky cats so thought this info might be helpful.