I'm a big fan of Glade PlugIns Scented Oil warmers. My favorite scent is the Hawaiian Breeze. They are also available in Jasmine & White Rose, and Lavender & Vanilla. Each refill lasts about 3 weeks or so. I usually replace mine about once a month, and it leaves a fresh, exhilerating fragrance throughout my home.
It is easy to find replacement cartridges for the plugins, and they are available in either single or double refill packs. I usually pick mine up at my local grocery store or Wal-mart. They last longer than candles, and a lot longer than spray-in-the-air fresheners that are available. They don't get overly warm, so having them around children isn't too much of an issue (other than them trying to plug them and unplug them if you aren't watching).
I am a smoker and I hate the smell that cigarettes can give to your house, furniture, and clothing. These air fresheners actually make it so you can't even tell I have a smoking household! My home always smells great...I wouldn't trade this product for anything.
Overall, I think this is a really great product, and much thanks to my mom for introducing me to them.