Answer: From your description I am envisioning a spot where the sun finally reaches at 3:00 in the afternoon when it is hot as blazes, and if it is at all windy there in the winter your choices will be further limited. The plants you mentioned losing are for the most part plants which do not tolerate harsh conditions and which really prefer ample moisture. In my experience pyracantha tends to winterburn in a windy site with reflected building heat, so that would not be my first choice, either. Since this is such a tough spot you might experiment with a few plants, see which ones do best and then fill in with more of those.
You might try some plants which are tolerant of a wide range of light conditions plus both heat and drier soil since you mention it is sandy. Junipers, mugo pine, honeysuckle (Lonicera heckrotti or L. sempervirens) and yucca might do. Flowering possibilities would be spring bulbs, daylily, sedum, salvia, veronica, thyme, purple coneflower and perhaps liriope (be sure it is a clumping form). Whatever you plant will have better chance if you can incorporate ample quantities of organic matter into the soil and widen the bed a bit so that they are not crowded up against the building where the reflected heat can bake them and so that rain can reach the root zone. Other things you should consider doing are adding a few inches of organic mulch such as shredded bark and paying very careful attention to watering for at least the first full year until the plants are well established.
Finally, you might also consider planting a small tree such as a redbud to shade that area from the late afternoon sun and transform the area into an all-day shady one.
Q&A Library Searching Tips