My grandmother's favorite--Lantana is so easy to grow. It attracts butterflies, loves sun and can tolerate drought. Good watering results in a showy and large plant. Freezes to the ground in winter but returns year after year.
Passion Flower Vine* Exotic flowers like these don't have to be limited to tropical gardens. A vigorous perennial vine that climbs via tendrils, the passion flower can be a conversation piece in the garden.