It's hard to say without knowing what's going on in the rest of the space, what you might need and if you considered planting it, how much light/moisture it gets and which zone you're in. If you need extra storage it would work as a tool 'closet', which might actually be a good way to store garden tools. If you wanted to plant I would go with a vine, as it would cover a large area without needing much depth. If this is something you would like, check out georgiavines.com, as they have a pretty amazing selection.

It looks like it gets some sun. What about planting raspberries and training them to grow along the fence?

Make a vertical succulent wall--I'm doing one on my narrow patio that will be in the shape of a square but the design will be a bi-colored labyrinth using the succulents--you'll be able to see it directly through the window from the kitchen. Install hanging pockets and make a lettuce & herb garden. Install trellises and grow your own food--climbers are available for spinach, zucchini, cucumbers, eggplant, small melons, small gourds, pumpkins. You've got enough space there to grow a considerable amount of food if you use climbers. Or install a vertical water feature if you need some white noise to help disguise the sound of neighbors.

Can you build some steps to hold planters? I'm thinking something like the risers a choral group stands on covered with wooden planters. Put an outdoor baker's rack in the center and risers with planters on either side.

Plant standard bay trees and under plant with buxus sempervirens or lavandula munstead. Have up-lighters behind stems of bay trees to give silhouette and hints of the blue lavandula at night (please remember to use low lighting! its meant to be subtle) . It would be best to paint fence same colour as house to tie everything in. Regards