The timing varies with latitude and microclimate, but in general, common milkweed reaches its floral maximum in midsummer. It would be a bit of an exaggeration to call the plants "magnificent" or "stately," but they are certainly impressive, rising 4-5 feet high with a thick stem to help support a half-dozen blossoms as big as softballs.
Through the summer months those compound blossoms provide an abundance of nectar and pollen not just for the Monarchs, but for other butterflies and innumerable solitary bees and other insects.
I posted earlier this summer about the complex morphology of the blossoms and how their strategy for pollination makes the blossom occasionally lethal to unwary small insects. That is an uncommon occurrence, and for the most part when one wanders through a patch of mature milkweed, there is an abundance of small insects hovering nearby (and often a resident crab spider lurking in the flower).
The fragrance is strong and reasonably pleasant, but not a prominent feature of the plant. Midsummer will also find the plant hosting a variety of other insects - aphids tended by ants, milkweed beetles and milkweed bugs, lacewings and their eggs, and the milkweed tussock moth. The ecology is complex and worthy of a separate post (next summer).
Next step: the spectacle of seed production.