I'm more of a bed-size quilt fan. I make most of my quilts twin-bed size, roughly 65" x 88" (longer if it's for a XL twin). Of course the pattern you're using will determine the exact dimensions.
Because most of my bedrooms - and most of those of my grown children - contain twin beds, sometimes put together to form an erzatz-king, I've found that if I make two twin-size quilts for those rooms, they serve well when the beds are separated, and they can be overlapped a little when the beds are pushed together and made up as an erzatz-king. They also aren't too bulky/heavy to be dragged out as a "nap-on-the-couch quilt," if needed.