When I can find it, I like the 108" wide fabric simply because it is less work and no seam(s) running down or across the back. I like batiks for backing, but use others also.
Elaborately pieced backings make quilting more difficult, but backings can become much more interesting with just one insert pieced in. A diagonally running band of contrasting fabric in the background can look wonderful. With blocks, piecing in just one block in a band or several blocks in a band can make the back a lot more interesting.