When making the contact page I wanted to have big social network buttons (the purple squares are placeholders). My first solution filled the whole width of the screen. I found it looks too intrusive as the buttons are too big. In a smaller browser window they looked more reasonable.
My second solution split the page in half to make the buttons smaller as well as fill the page a bit more. When the window is made smaller the left part of the website goes below so to make optimal use of the page space.