Butterfly Weed, Asclepias Tuberosa, zone 3, 24-30", June-August, prefers full sun-part shade and well drained to dry soils, butterfly magnet!
Butterfly Weed, Soulmate, 42", zone 3, rose-pink flowers in large umbels. Butterflies find them irresistable. Blooms mid-late summer into fall. Full sun-part shade.
Delphinium, Belladona Bellamosam, 36-48", zone 4, blooms mid-summer into fall. Full sun - part shade.
Foxglove, Large Yellow, Perennial, 24-36", zone 4, hummingbirds love these. Blooms early spring - summer. Part sun - part shade.
Echinacea, Magnus Superior, 24-36", zone 3, Attracts butterflies. Blooms July - September. Full sun.
Balloon Flower, Fuji Blue, 24-36", zone 3, Long blooming. Blooms June - August. Part shade - light shade. (I've had great success in full sun also.)
Helenium, Helena Mix, 48", zone 3, Attracts Butterflies. Long bloom season, July - October. Full sun.
Heliopsis, Burning Hearts, 36-48", zone 3, Excellent late season flowers, August - October. Full sun.
Lupine, Russell Hybrids mixed, 36", zone 4, a wide array of solid and bicolor colors, June-July, excellent as a single specimen or planted in groups, full sun-part shade, rich moist soil
Oriental Poppy, Haremstraum, 36", zone 3, Dazzling mix of colors. Blooms late spring and early summer. Full sun.