How much sun does that area receive? What direction does it face? I like your fountain and the beds look very neat. I would think a leafy plant like Louisiana iris would soften the bottom edges of the fountain. For me, they are evergreens. There are also day lilies that are evergreen and can fill out nicely. I have had fantastic luck with Jungle Princess. They bloom longer than most of my others and are very care free.
You could also place a trellis between the windows and behind the fountain and put a flowering vine on it. It would not necessarily have to attach to the house and would help break up the wall. I have a trellis attached to my fence that has Jasmine on it. When it is in bloom, it is gorgeous and when it isn't the evergreen leaves are nice. The only thing I would say is that it does require trimming. I have let mine go a couple of years and now I will have to hack at it unmercifully to get it back in bounds, but that is my fault.
Under the windows, could you use a small Encore azalea? A nice red is Autumn Embers. I believe it gets to 3.5 - 4.0 feet tall. For me they bloom 2-3 times a year and are evergreen.
You could add some annuals around the front border to add some color. I am also coming back around to Aztec grass. The variegated leaves are nice and geez, it can live through most any weather or care level.
I understand what you are saying because I just redid my front beds and went with almost everything evergreen, so that no matter what the season, it should look fairly full. I used Gardenias in the back of my beds, Loropetalum in the middle and dwarf Ixora and a mixture of perennials in the front. When nothing is in bloom, the differences in color of the foliage adds a lot to the bed or at least I think so.
Okay, so those are my ideas. Hopefully someone with more experience will come through, but maybe there is something here that you can use.
