Complementary plants in this small space
So I have this small area in my back yard. It's on the north side of my house in zone 9. It gets "full sun", but is somewhat shaded by the house, but no trees, etc. It's full of these flowers now, which I think are either iris or some type of lily. (On the far left is easter lillies.) My wife loves the flower that comes out of this plant, but it seemingly will flower once, and then the flower lasts a few days then dies. The rest of the year it's these kind of harsh looking tall blades of grass.
My question is what kind of flower/plants can I put in here that will complement these, and give flowers all year around (or at different times of the year.) I was thinking that I could put a variety of daylillies, or perhaps some other types of plants/flowers. I'd just like it to look a little more interesting for most of the year.
Thank you for any suggestions