Nice layout!

Just for experiment, change the wall color to a dark blue or red and see what that does. As you've seen with my rendering, the beige walls came out very pale, almost white, and the beige shade that I had chosen was much darker.

Did you try the built in renderer? (the one with the black camera icon from the menu bar) Just wondering if that would give a nicer result. I've noticed that it renders things a bit differently.