Great looking garden! I have a house but the yard is under mainly shade so I use the backside of the house where we have a 3' run with lots of sun. I have many raised planter boxes. Been gardening this way for 3 years now. This year have 6 zucchini plants, 6 Kentucky wonder pole beans, sage, cilantro, basil, 17 tomato plants (sweet 100 cherry, sungold cherry, early girl) and am thinking of what else I want to eat this summer. There's nothing better than grabbing fresh veggies from your garden for dinner. It just tastes so fresh and feels so good! I wish I had chickens although I don't think living in a city in a rental house allows that. But great looking garden!
From what I've read, you can get a lot of veggies out of the planter boxes if you do it right. I grow my peppers in boxes in front of the house (the brick facade lets me plant them sooner and keep them growing longer) and they did well last year.
If you like hot peppers I'd recommend growing some jalapenos. They're pretty easy and they produce all kinds of fruit. I usually grow 4 plants and I get enough peppers for two batches of jalapeno jelly, plus enough to dehydrate and store over the winter for stews, chili, etc.
I'd say you could try beets because they're pretty easy, but they take up a pretty good amount of space for what you get.