Common Milkweed is a tall plant with wonderful sweet scented flowers. The scent is strongest in the evening and it attracts many different butterflies all day and moths at night. Humming birds love it and last summer we saw orioles visiting the blossoms as well for the sweet nectar. I tried and tried to get a picture of that but never got one.
Spider Milkweed is a low growing plant that would look good mixed into the front of a border.