The first Summer Quilt I made I didn't put any sort of batting in it. It is fine; we enjoy sleeping under it.
The girl who quilted it said it would have been easier to quilt had there been some sort of batting. She said that with no batting, it wanted to slide around.
The one I am working on now I am putting a flannel sheet for batting. With the back using Flannel, it will have a little warmth for Winter, and I hope it isn't too hot for Summer! Mariah