I'm usually a windows open for at least part of the day girl and only oils in the mix when cleaning, but we just lived in Darwin for a bit where everything is musty and damp, and like Astolady, I loved my aromatic reeds. YOu can get them in lots of places.
I have climbers too and can't have candles or oils burning. Another way I sometimes do it is put a couple of drops of oil on a cloth and wipe over cold light bulbs. That way when they're turned on they heat the oil and emit the fragrance.