For something "Full' in a blazing hot place, I would think to grow some tough
but pretty ornamental grasses. Some miscanthus, pennisetum, and others can
get big, have really nice blooms, and although they may not be evergreen I like
the way they look when not cut down in the winter.

just my first thoughts and 2 cents.

You might could try Yaupon Holly, it can get spindly without pruning, but I would think with pruning it would get bushier. Some of the lower growing palms like Needle Palm or Bluestem Palm may work too.

we have dwarf yaupon holly around the foundation at work.
they are small, rounded (pruned into those "meatball" shapes) shrubs resembling boxwood a bit and are planted in areas mulched with brown, crushed rock. doesn't get much hotter than that and they aren't fazed by the heat around the root zone and also get reflected heat from the bricks.
depending on your zone, loropetalum might also work. some of the newer cultivars are supposed to stay smaller but some can also get very large.

Thanks for the ideas! I'll keep them all in mind. For the time being I've cut back the existing shrubs and I'll see how full they come in this year. I've decided that this is lowere in the priority list than a rock wall, french drain, pea gravel path... :)

What zone are you living in? Up north near Huntsville is a lot different than over in Baldwin County or Mobile. If up north, you have a few more options than we do here in z8B.

I have one side of my house facing south, and it is white stucco, which keeps heat from radiating on the plants so much. And, this portion of my yard is behind a privacy fence where I have decided to make it appear tropicalesque. I use that term because I'm influenced by the forum of that name here on GW. But since that is fairly hot and only gets shade after the late afternoon, I have had to find plants which do not need to have wet cool feet. I do have some butterfly ginger there, with a dark background row of aspedistra and canna lilies which do not grow too high. I also have butterfly weed with multicolor blooms like lantana, and in front of that I have the leriope and some kalanchoe. Surprisingly enough, the kalanchoe has been blooming this winter even during the harsh cold spells--all I did was throw some pine straw over it and it kept going.

In the front yard of my house, which faces west and really catches heck in the summertime, I have some daylilies behind some dwarf nandina Firepower, but I'll be changing those into the regular looking dwarf nandina. Two of the camellias punctuate the corners of the house where they can get some air circulation. I haven't pulled out the small-leafed azaleas yet, but will move them all next fall if they survive summer in this location. They are an intense fuscia color when blooming, but don't have dense leaves in this hot place.

I do recommend the fan-shaped palmettos, they love the heat. However, once they are in the ground and prospering, it is almost impossible to dig them up. They really know how to grow a root that can squeeze every last drop of water out of dry soil, I think. Don't put them where you have underground gas lines or water lines if you think you may have to ever dig them up. I also think sago palms might work, with their lustrous dark green fronds. They do get immense though, and might need to be set away from the house, or used at the corners. I used two mugo pines which can grow 36" diameter and about that high, up in z5B MA, and I am now trying the Buxus "Green Velvet" down here in z8B but not next to the house--just along the front of my new rose bed. I know they can take the cold without too much problem; we'll see how they do with the heat and lack of pruning--I do not believe in trimming hedges as a way to spend a day in the garden.

Not very organized in my post this time, just what pops into my head.

I planted Butterfly bushes last spring and they are 5ft tall in bushy already. I planted the Nanho Blue. This plant looks pretty and does not need much fuss. Can take full on afternoon sun. Attracts butterflies and the RARE to see Hummingbird Moth.