I love the fun of pieced backings, especially when I can use up a bunch of the material I used on the front of the quilt. My daughter's wedding quilt had a zillion seams on the front and I used a bunch of the scraps to make the backing large enough - the quilt is 115 X 105 and I didn't have enough black and didn't want to go out and buy more when I had all this lovely pink fabric! I had no problems quilting through all of it.

I like all my quilts to be double sided, so I use fabric that is a compliment to the front, and of the same quality so I have to piece.