I've recently switched to the Arm & Hammer Flushable litter. Since I keep one of the boxes in the bathroom, it's really rather convenient. The best way to reduce odor is to scoop the box frequently, and since I see it more and don't have to take out the trash every time, this helps me.
I use Fresh Step and clean it every morning before i leave for work and when i come home if needed....after i scoop i use Tidy Cats deodorizer across the litter....and i put fresh litter in once a week. I also change out the filter in the litter box every 2 weeks or so. I live in a small one bedroom apartment and the only time i notice smells is when i'm gone for a day or two but that is to be expected. (and after she drops a hot one!) whew!
P.S. I believe my mom used Tidy Cats for muliple cats....she has 4 cats.