For air "enchancement" i like Bath and Body works WallFlowers. Nice scents, nothing fake smelling and it will fill a room nicely.
But, to get rid of bad smells, i use Febreeze AirEffects or whatever and that helps with stinky air, although the scent does not last.
If you want to do something at a local grocery store, WalMart, etc... I like AirWick Air Wizard to plug it in. nice scents as well and will last a while