Built in idea for the dining room door! Oh how I love built ins. Ikea Shelves Into Built-in Bookcases :: I really love this. You could turn any room into a library with this idea. And you don't need ikea for it, either.
Principles of design: Balance: This could at first appear to be symmetrical, but when you look at all the elements, such as the drawers on the left & the ottomans on the right, it makes it broken up more so it's not in such tight symmetry.