I like the idea of metal art on that big blank space -- something with some color. Also a colorful door mat, maybe a rug under your chairs, a small table for a glass of lemonade, house numbers (above the porch?), and some plants. Oh, and a pretty wreath for the door. I really think you need COLOR -- you're already swimming in neutrals.

I know you say those aren't your chairs, but measure them -- then buy something a bit bigger. They don't come anywhere near "filling the space". Your porch appears large -- you might need something larger, like an outdoor sectional or a large outdoor sofa + a matching chair.

Here are some inspiration pix I like -- I particularly want a chaise of some sort because I'd like an outdoor reading spot, and I want space for 2-3 people to sit comfortably. What function do YOU want for YOUR porch?