Antony and Cleopatra is a kind-of-history play about two of the most glorious societies in the Ancient World. Shakespeare used his poetic skill to spruce up history, to great effect. The scenes about Egypt are rich in language, playfulness, and the natural world, but they’re tempered by the more serious and severe tones cast by the military figures elsewhere around the globe in the play. Caesar puts it best after he finishes partying on Pompey's barge on the night of the truce: "our graver business / Frowns at this levity." The play is decadent in language and content in some parts, and absolutely brutal and soldierly in others. The result of these contrasting tones is a richness that reflects the duality of the action.
The other effect of the complexity of Shakespeare’s approach is that the audience is constantly unsure of what will happen next— whether things will go the Roman or Egyptian way. By maintaining these peaks and valleys of action, sometimes reasonable, sometimes passionate, the audience is kept guessing and wondering what tone Shakespeare will use next, and on which he’ll eventually end. (Which one is it? Good question.)