debonair

because "debonair" seems limited to men (although it need not be—in L'Allegro Milton used it to describe a goddess), you may want alternatives: sophisticated, jaunty, lighthearted, vivacious, breezy, nonchalant, free and easy, merry, cheery, sunny, sporty; well-mannered, well-bred, polite, refined, civil, charming, suave, courteous, urbane, gracious, graceful, obliging, affable.