You need a pretty big space to make a 75-inch TV feel like it belongs. The best way to ensure that it's going to fit well in your room is to measure the distance (in inches) from where the TV will be wall-mounted or placed on a stand to where you will most likely be sitting, then divide that distance in half. So if your couch is about 150 inches (around 12.5 feet) from where your TV is going to be, then a 75-inch model will be just about the perfect size. You can, of course, go a bit bigger or smaller depending on what is available from each brand and what your budget allows. But a screen that is too big may overwhelm your space and even cause motion sickness, while one that is entirely too small will make your room feel like a giant cavern and force everyone to crowd around the TV to watch the news.