Yesterday, I was talking to another quilter who was having trouble handling a large quilt on her home machine. She mentioned that anything over 60" wide was too hard to quilt on her machine. Perhaps you may also have had the same problem so I thought I would mention a method I've used.
Lay out your quilt for basting -- the backing, the batting and the quilt top. Pin baste the center section from top to bottom of the quilt. On a 90" wide quilt, this would be the center 30". Fold back the side of the quilt top over the basted section, exposing the batting. Without cutting the backing, cut out the batting (you will replace it after quilting the center section). Repeat for the other side of the quilt. Now you have batting only in the center of the quilt, making it much easier to handle under your machine.
After machine quilting the center section, lay out the quilt again. Reinsert the side batting, butt the edges of the batting and hand stitch together. Pin baste and quilt the side of the quilt. Repeat on the second side. Because you are quilting closer to the edge of the quilt, you will be able to handle the additional weight and thickness of the batting.
This does require you to lay out your quilt a second time, but the ease of quilting may be worth the effort. What do you think?