One of my favourite plants for fragrance is Nicotiana. It is a relative of the tobacco family; and, is not particulary attractive. However, the scent on this plant is intoxicating. The flowers open at night, closing by day.
This plant is best situated behind other more spectacular bloomers or up against a fence. Plant this and in the long summer evening, when windows are opened late into the night, your breezes will be sublimely fragrant.