I want to make my mom a lapquilt for Christmas from a Moda layer cake. 60 x 70. I want to use one of the prints from the fabric line for the back. Where should I put the seamline so it is least noticable? Down the middle? Or should I use the 44" width of the fabric so I don't lose the design and piece at each of the sides? Is that clear at all?

I would use the second option :D:D:D

experts say to double seams on the back into thirds rather than one seam down the middle
If you plan to piece a back, just sew pieces together in a way that pleases you and will please your mom

I usually open my fabric, match right sides and sew it into a tube. You can cut the tube apart one of the fold lines and then you can have a wide piece in the middle and a narrow pieces on each side. Check for a tutorial because it will explain the technique better and you will be less likely to make a mistake. I speak from experience about that.

For me it would depend on the way I was going to quilt it. If I needed to put it on the longarm a certain way for the design to look right, then I would seam it so that the seams go across the length of the poles. If it doesn't matter how it is loaded on the frame, then it doesn't matter which directions the seam goes and I would do it the best way to use the least amount of fabric. Clear as mud???? I am sure everyone has their own way, this is just what I do.

I agree, 3 sections on back, no middle seam, my quilt bible says that is best. Middle seam will be stressed .

I'm sure you'll get a variety of opinions!

If it's a small busy print, I've pieced down the middle. Some people frown on this because they say it puts more stress on the seam (from the folding maybe?). I've never had a problem with mine.

If I'm using a large print and have enough to match (as close as I can), then I might do that. Sometimes I'll use a strip of another fabric between so that I don't have to match if I don't have extra. Sometimes I do this and use up some of the blocks/fabrics from the front just to be decorative.

You can also seam both sides, cut one side down the middle, which leaves a full width in the middle and 1/2 on each side.

They all look fine. I think it's a matter of preference.

Seams down the middle often get stressed because so many of us fold our quilts down the middle. If we fold our quilts differently, the middle seam is fine. I like your idea of matching the print if you can.

I make a tube first. Here is a tutorial.

http://www.reddawn.net/quilt/backings.htm

I would piece each side of the 44".