Synonyms:
* Commonplace: Ordinary, unremarkable
* Dull: Lacking excitement or interest
* Mundane: Relating to ordinary life; lacking excitement
* Uninspired: Lacking creativity or originality
* Banal: Lacking originality or freshness
* Tedious: Tiresomely long or dull
* Flat: Lacking in interest or excitement
Antonyms:
* Exhilarating: Exciting and stimulating
* Inspiring: Filling with an urge to create or achieve something
* Original: New and different
* Creative: Producing new and imaginative ideas
* Imaginative: Able to form new ideas and pictures in the mind
* Poetic: Relating to poetry; characterized by beauty of expression
* Lyrical: Having a pleasing and musical quality
The best synonym or antonym for "prosaic" depends on the specific context in which it is used.