one more thing to add about litter: After basically trying everything, I've found that using pine pellets (also used in horse stalls) are the best. They're also the cheapest when compared to everything else (about $5-$7 per 40lb bag). They puff up when they come into contact with liquid, so they can even be composted if you have the capability.

I find that if you clean it on a daily basis, the litter box doesn't smell at all. I found the clumping kind to be the worst in odor control and keeping it clean, and I also had my male cat get a slight urinary tract irritation from what I believe was the clay dust. And they're so bad for the environment.