7" is perfect to put in your inside pocket, for the train, bus or airline journey. It is big enough to watch a movie at arms length or in your lap, and ultra portable. Keep your 13" for the house, but it is not as portable or as usable as the 7", if you must stretch the screen width ways to get an 8" or 9" and keep it poketable but 10" or 13" 4/3 aspect ratio no thanks.