36 x 40 is a good size. Flannel on the back works great. A small pocket on the top front for their small items is nice. And a pocket of sorts-just extra fabric folded, and sewn across the entire back lower portion helps for their feet. Have cut bottom corners at an angle to help with not getting caught in the wheels. I also keep quilting an open design so the quilt is more "poofy" as they say. Hope this helps!
