Synonyms:
* Positive: courteous, polite, kind, hospitable, charming, affable, pleasant, agreeable, benevolent, generous, compassionate, thoughtful, considerate
* Formal: elegant, dignified, stately, refined
Antonyms:
* Negative: rude, impolite, discourteous, unkind, inhospitable, harsh, unpleasant, ungracious, unmannerly, boorish, arrogant, disrespectful, mean, cruel, uncaring, thoughtless
* Formal: vulgar, crude, indecent
The specific synonym or antonym you choose will depend on the context of your sentence.