Because I like the wood against your walls, I would think about leather or a chestnut brown or copper colored sofa. In fact, I think everything about this sofa, chairs and rug tones would work in your house, especially if you already have a rattan chair. These walls are Agreeable Gray.
The same blog shows a gray sofa with Agreeable. See how the gray makes the walls look beigier? Your tastes seem more colorful than this scheme.
I'd also encourage you to take your time and make a mood board for this room. A sofa is a big purchase, and you're furnishing the totality of a room in your new house, not making an isolated decision. Maybe hold off on the chair upholstery until after sofa purchase and entertainment center arrives? Good luck. Love your backsplash!
Q