We have two cats. And for anyone who has cats (or knows cat owners), cats can be very stinky. Our litterbox is in the basement bathroom, next to the office area and playroom -- where we spend lots of time. We need serious odor elimination. We've tried many types of home fragrances. So far, Febreeze NOTICEables has been the best.
Febreeze NOTICEables is a plug-in scented oil warmer that "automatically alternates throughout the day so you don't get used to the same scent". For those unfamiliar with Febreeze products, they are designed to eliminate odors in the air caused by bacteria. According to the package, it should last about 30 days on the low setting. They are easily refilled and can be found pretty much everywhere.
Now, I don't know about the odors caused by bacteria, but I do know that it does a great job eliminating odors caused by cats. We like the "clothesline breeze/meadow songs" scents. They are clean and not too-perfumy. This one little oil warmer really does make the whole basement smell nice. I gave it a 4.5 overall -- only because I seem to constantly be buying new ones. I use it on high, though, so it doesn't last a full month by any means. Plus, if you leave it in too long, I've noticed a burning-smell. which is not good in any case.
I recommend this product highly.