Not exactly QAG, but I forgot to mention quilting in sections. I used Debra Wagner's method (I'm sure very similar to Marti Michell's) which involves cutting just the batting into sections. Basically what I did was lay out the batting on a large table, cut the batting into thirds using a large S motion (so I wouldn't end up later with a straight line join, but also this makes matching up the cut edges easier) from top to bottom, then used a black permanent Sharpie to mark registration lines through both pieces. The registration marks are really necessary later on to match up the batting pieces. I also Sharpie marked top and bottom of each piece (if you don't, you can end up very confused later if one piece gets turned back to front). I stored two pieces of the batting -- the middle and right side. With the left side of the batting, I layered and basted the quilt -- being sure to leave about 6" on the right side to make adding the center batting easy later on. The excess top and backing were accordion folded and lightly pinned together. This made quilting the entire left side of the quilt easier, as there was very little bulk to control under the machine arm. When done with the left side, I went back to the large table, matched up the edge of the middle piece of batting with the piece already quilted, and layered that section of the quilt.
It was work, but was worth it to me because it made the machine quilting much easier. Afterwards, you could not tell that the batting had been pieced.