I looked at your photos and wondered if you are in the Southwest, and immediately thought of xeriscaping, which is creating a space that uses very little water and suits its environment and is easy to care for. In such a garden there are one or more paths and sitting areas using bricks or flagstones or cobblestones or even very fine pebbles. The rest of the area is covered with mulch (there are some attractive mulches available now, finally) in which are planted the trees, bushes, and flowers. Watering is infrequent and there is no lawn to mow. I think that it's a beautiful look that would enhance your space and inspire your creativity. We changed our dismal front yard to xeriscaping and I am so happy with it that it's a major reason why I don't ever want to move. Here are some details about creating this kind of yard, but it can be considerably easier than the article suggests, especially since yours is so small.

You could paint whichever walls you like and also the door; it would contribute a modern flair and additional interest. The great thing about paint is that it's pretty easy to change the color if you tire of it.

I love the idea of growing one's own mint for mojitos!

I would first start with the backdrop of going vertical . It will take some research but potted bamboo would be great in some areas. It grows fast. Mine have reached over thirty feet in two years.

Other areas could get a living wall.

These IKEA outdoor shelves are cheap and great. You can keep the shelves on in some areas, in other areas hang outdoor art. You can also cut the long pieces off and stack them up a wall.

When you are all done with the vertical part you can add some hardscape with walking stones or whatever as well as create planting beds where there is room.

I appreciate your ideas and comments! thank you!