Personally, we have had fantastic luck with the charcoal air filters, cut way down on the animal smells. They actually impressed me more than I thought they would, we have a pretty decent number of animals, and not a huge house, so we have to be extra diligent or things turn quickly, and it's easy for animal smells to start getting overly strong.
Only downside with the charcoal filters is that if you have a lot of bird dust, they clog *so quickly* My three month filters last about 2 weeks before I have to vacuum them out.
We also use baking soda pods hidden around the house which we replace monthly to help absorb odors, and get fresh lavender from our neighbor when she harvests it which is also a natural deodorizer. Less about adding good smells, so much as just preventing bad smells from ever building up. I doubt anyone ever walks in and thinks "man, this house smells so good", but, they don't think it stinks either. It just smells, normal.