Gimgim,
For decideous, I would plant a small form of crape myrtle there, mabey a pretty purple.
I bought a gorgeous dark purple one from Lowes last year, the color would look fantastic there, and they take the sun and bloom all summer.
There are different kinds of crapes, they have really small ones, then they have medium sized ones, (which is the one I would put there), and then they have the trees.
What I would do is wait til the end of May when they start to bloom, and then visit the nursery. When it is blooming, you will know exactly what color it is.
Then you can bring it home and put it where you want to plant it, and see what you think. Don't get a variety that grows more than 10 feet tall,
They also take pruning very well too, just in case it gets too big.
For evergreen, I think I might look for a "Teddy Bear" magnolia. It grows real slow, so buy one about 4-5 ft. tall, and it will keep it's beautiful two toned leaves all year long. It loves, loves the hot sun and the blooms in spring smell soooo good like fresh lemony perfume.
Southern magnolias grow really slow. So don't think it will outgrow that spot anytime in the near future.
Good Luck to you.
Love your jap maple, it looks like mine.

The Crape Myrtle idea is a good one but I am concerned about the spread. If I chose a smaller variety, how much room would I need to give it so that it would not hit the brick or the steps. I looked online but cannot really find info about the spread. I could bump out the line of the bed to make more room but that would require moving all the day lilys to the "new" edge of the bed. I definetly do not want to plant something that would not have the right amount of space (been there , done that!)

If you went with a medium grower, the spread would be alright for that space.
Crape myrtle blooms on new wood only.
That is why many people insist on pruning the myrtle in the fall, cutting the branches back so that when it grows again the next year, it will bloom on the new growth and not outgrow the space.
Crape myrtles live very comfortably in very little root space. That is why they are planted in parking lots and next to side walks quite often, they can put up with alot of abuse, and still flourish.
The medium size one I bought was very little, and it will take quite a few years for it to get to the 8-10 foot size that was on the container, but when it does get too high, or in your case, the spread oversteps your bounds, you can just cut it back good in the fall, when all the leaves fall off.
There are quite a few web sites on the internet that have the different varieties and their characterstics but I found to buy them when they are blooming is the way to go.
That way, you will see exactly what the flower looks like so you are satisfied with the color.
Usually private nurseries will have a nice selection, and hopefully, they would have hired someone you can speak with about the size.
The real small dwarf crapes are also gorgeous. THey don't grow too tall at all, take up less space and grow nice together, so that is also a nice alternative.
They are small though, but the space you have is more than adequet for a couple or three of them, and you can mix them up if you want.
Mabey a purple, a pink and a white.
I'm talking about the real small ones, they don't grow very big at all. But they will flower if they are planted in rich soil and fertilized every year.
Mabey put a cute little staute of something in front of them.

A butterfly bush is always lovely and they have white, purple and blueish ones, and while they attract HUNDREDS of butterflies and bees, they don't have all-season interest. A holly is a wonderful option for your space, evergreen and gets berries which birds will eat in late winter. They come in various heights, so read the tags or research before you buy. Be sure to get a female holly, if you decide to go that route. Their flowers aren't much, but their foliage is lovely all season. Best of luck to you! :)