I have machine quilted 107"x106" in a sewing machine with a 6.75" throat. :) (and many others mostly in the 85"-90" square size), what sort of information are you looking for?
1. You need to make sure you have the quilt supported so it wont pull on the machine. A table or at least a chair for the quilt to sit on will help wonders.
2. BASTE, BASTE, BASTE, the better you have your layers basted the less chance you will have of puckering. I perfer batting from the Warm company as it bastes well and quilts nicely. I have used poly - that was the one and only quilt I've done that ended up having puckers, if that tells you anything.
3. Firgure out how you'd like to quilt it, and plan a course of action, and then go for it.
4. Try to make sure as you move the quilt around that the quilt doesn't end up "doubled" back on itself in the arm area. I know some tv shows swear by "rolling the quilt, but I've found that with the styles I pick to quilt it's easier to stick it in and go with it. :D
Some people like a walking foot, I personally don't use one, I quilt just like I sew. I have used a quilting guide, which is a bar of shots that follows along your line to provide a nice offset, that works well.
And last but never least is you want to free motion it talk to Izy because she did one your size in two days.