In older websites, the standard is usually 960 pixels, because it has a lot of factors that it can be divided into, and most monitors were 1024 pixels wide. Recently, a large portion of laptops are 1366 pixels wide, so the answer may immediately be assumed to be something around 1200 or 1280 pixels. However, there are also desktops, TVs (HD and 4K), and I've recently been seeing some new computers that are up to 3200 pixels horizontally. Okay...
My point is, how should a website use up all this extra space? I'm thinking of scaling the site to match the width of the screen. Is this a good practice?