I would remove the brick encircling the dirt and get stone and build up a little wall around each area...backfill with dirt and plant some creaping Jenny, along with some flowers and grasses. You could plant a ornamental Japanese maple as well. Add a small fire pit area with stone...place wood or wrought iron seating around the fire pit.

Could add a trellis in a pot with ivy to screen the electrical box as well

Could also stain the concrete a brown or shade color from the stone around the fire pit. Get a high grade concrete stain.

Put Japanese maple in area under window

Set it up as a room, with some color. Where you do have dirt, plant some interesting varieties that grow well in your zone. I would also put some shutters on your window and maybe a window box.

Hi, I would first think of what I wanted to do in which area, where is the sun, where will you sit, do you want a barbeque area, a sand box for the kids, where are your doors, etc. You should make a list of what you want first dan make a drawing with measurements, direction of the sun , where is sun in the evening / morning? Do you want to sit in the sun or do you want shade, where is this patio? If its in the desert you'll need different plants then if it freezes in the winter. Do you like gardening? If you don't I'd go with lots of potted plants.i.e. if it doesn't freeze in the winter. I would like to see the space divided up visually into "rooms" this way your patio would look wider, and have more mystery if you can't see the whole thing at once. Do you want modern or traditional? Lots of green/flowers?

You've got a huge expanse of concrete and tiny planting boxes. If you want a lot of hardscape, then widen the planting boxes along the fence (and make them continuous along the fence) and keep the rest. Otherwise, tear most of it up and stick in grass (leaving a path, if the area is well travelled.) You can cover your cracking concrete with something nicer looking.

You should take pictures of your area every hour or two to get an idea of what kind of sun you have. You probably have a huge amount of shade between the fence and the house. "Southern exposure" means nothing if you aren't getting much sun. You can have a lush and low maintenance garden with shade loving plants like ferns. You should get some climbers to cover the fence.

Don't be tempted by plants in planters, as they often need a lot more watering. When it hasn't rained, there is usually moisture deep in the ground that roots can reach. When your planter is dry, the roots are dry.

With a few plants, would could have a really nice yard, not something that looks like a prison yard.

This area has a lot of potential for a restful, private oasis, and I see many good suggestions above. I would suggest breaking up the rectangularity of the space by combining planted areas and hardscaping that incorporates curves and circles into the design. If you plan to keep the tree where it is why not create a circular pebble mosaic patio surrounding it for a seating area. Then consider an arcing gravel or combination pebble and flagstone pathway curving around the corner shown in the picture. A water feature might also be a lovely addition. Give equal thought to greenscaping and hardscaping, incorporate organic curves into the design of beds, pathways and patios, and you won't go wrong.

I love Dytecture idea. that pic looks great. It is way to hard edged now.