Maybe create a few separate areas back there?

What's nice about your backyard is that you can see it all from your back porch! Maybe plant pretty bamboo along the back frnce, but be sure it isn't an invasive variety or the bamboo will spread everywhere! You could also add a water element like a fountain or even a birdbath in the back right corner. Since it's somewhat shady there, you'll have less of a problem with keeping the water algae free and you'll be able to see it both from your back windows and also from the porch! Perhaps a rock garden around the base of the fountain?

Hi cmmrakich
Both these inspirational pics are easy to execute if your skills are Handy , the second pictute is more apt for the tree in the corner .