As far as butterfly attracting flowers go my Bougainvillea always attracted a ton of different butterflies (and lots of monarchs) and hummingbirds. I just ordered a new one since the last one I brought in for the winter the cats knocked off a cabinet and then my dog ate it
I can never find them at any garden stores or anything (though that's where I got my first one) but you can order them online and they're stunning.
They don't survive the winters, but they're super easy to keep potted, cut back and bring in over the winter. Just over the summer they will grow into a huge vine (just attach them to a trellis or something) and grow lots of flowers. They're a low water plant too, which is nice.
Not trying to threadjack, I just had to share since that's my favorite flower and I try to convince everyone else to get one
Maybe if more people buy them more stores will carry them.