I find fabric wrinkles more when dried in the dryer. If fabric pieces are small (one yard or less), I iron them dry on a commercial ironing board. If larger than 1 yard, I either hang the piece over the shower curtain rod (no crease) or I "bunch" it up and dry it on a flat surface (but more wrinkles this way). I have not tried the vinegar and water for taking out the wrinkles, but this is something I will definitely try tomorrow as I press my DH's shirts every morning.
As to quality of fabric, I've had fabric that wrinkles badly from the LQS and fabric that wrinkles badly from the big box stores. I also believe that the finishing chemicals are to blame for the wrinkles. I, too, find that looser weave fabric (the almost "gauzy" ones) wrinkle more.
Also, many of you mention using starch. I never use starch because bugs are attracted to starched fabrics and will "eat" the fabric (they are actually eating the starch, but the fabric suffers). If a quilt is stored and not used regularly, there is more of a chance of this problem.
This is just my opinion and what I do. I'm not telling anyone that they are wrong in using starch.
Anita