Sashiko quilting (Japanese) uses something like a #5 perle cotton to make big stitches. It looks lovely especially done in the clamshell design on blue denim. They use almost a crewel needle for that type of quilting.
As to quilting stitches showing: I handquilt a whole lot of my stuff. I WANT the stitching to show. The Amish use black thread regardless of the color of the quilt so that the exquisite quilting shows. I am trying to get as good as they are... but it isn't working. I can get maybe 8 stitches to an inch, not the 12 in a wall hanging I have made by some Amish sisters which is white and is quilted with white. It is truly beautiful.
I decided long ago that if I wanted to do something big (bed sized) I would tie it. I handquilt most of my wall hangings. It is relaxing and I get kudos for the quilting, not just the pattern, color arrangement, etc. And as I make a lot of Amish style quilts, my quilting shows nicely.
I am presently machine quilting a wall hanging that has about a zillion seams and I wanted that quilting to show also to add to the beautiful colors. Besides, handquilting over seams is NOT much fun. I chose a wavy decorative stitch that shows up on the strips. However, machine quilting is not my style. I have a Flynn frame, and several other things that would make machine quilting fairly easy, I would think, but I prefer sitting down in the evening with a quilt in my lap.It helps to unwind me after a long day at work.
Okay, lunch is over... back to work!
Anita