I need ideas on what to plant here. As you can see I need something to fill in this big space, especially between the two windows.

The tree is staying as is the porch on the left, so this is my space to work with. The small green plants are well established and thrive here (they were here when we moved in two years ago). This is a deep bed and so I have plenty of room behind the small green plants. I am also posting a photo of one of my side garden beds that shows some grasses that are doing well.

I would consider one of these also growing in this spot but before I go purchase something I want to make sure it will grow here. This is a high shade area in the front of the house though (lots of trees) while the side is nearly full sun. So I'm not sure how the tall grass will do in the shade (can someone ID these grasses for me? Pampas family I believe). I also wouldn't mind flowering shrubs but want to maintain the southwestern style garden, so also can't decide what flowers would fulfill both the space requirements and the SW design. I welcome any suggestions!!