I love to use aromatherapy candles in my home, and I know that I've written about their use in the past. My favorite candles are from Arbonne International -- which I use exclusively since I also own my own Arbonne business, and the scents are fantastic!
However, to get that instant home baked cookie smell throughout my home, prior to guests arriving, I keep a supply of cookie dough in my fridge. My favorite cookie dough aromas come from Pillsbury's refrigerated gingerbread dough -- I just roll it out directly onto a cookie sheet, pop it into the oven 20 minutes before the guests arrive, and enjoy the fragrance!