I recently finished a quilt for myself 110 x 120. And one for my daughter 110 x 116. We both chose yard goods. Use 1/2” Seams pressed open and plan for the seams to go horizontally across the quilt instead vertically. A vertical seam is more difficult for a long arm quilter because all the extra fabric in the seam wrapped around our roller makes the center tighter than the edges of the backing and there is a greater chance of a pucker or fold in the backing. We are a LA quilting business so have experience with this. Also there is a lot of difference in the quality of Wide backing. I ordered some from Missouri Star Quilting and it shrank 5” when I prewashed it. So I still had to piece the back.