MIL wanted a quilted bedspread that reached the floor so her sister made one for her. After using it a very short time she and FIL decided it was way too heavy, so had it cut down. My quilted bedspread reaches the bottom of the box springs, so I don't use a dust ruffle. It is heavy enough to stay in place but not too heavy to move when needed. I used W&N batting. It's been on my bed for a year and both DH and I are happy with it. Washed for the first time yesterday, and I was able to wash it in my home washer and air dry in the dryer. Came out quite nice.

The Warm Co. makes Soft & Bright (100% poly) and Warm Blend (50% poly 50% cotton). Either would make your quilt easier to handle and launder. My experience is that both machine quilt OK.

I would go with a lightweight poly because the weight will be significant with the quilt being so large.

I made a queen bedspread from my first pieced top. I made it to fit the top of the bed then attached a bed skirt for the drop. It was a bit short so I added a band of wide Irish lace to the bottom of the skirt. I was lucky to find a premade skirt that matched.
I backed the top with a sheet, no batting because l wanted to use it year round.

I enjoyed reading this post, because I want to make a summer-weight quilt for our bed. I've chosen a Kansas Troubles layer cake and cream tone-on-tone yardage for the background. This all should go together quickly, as I will be using the D9P pattern and the blocks will be huge! I appreciate the input on the batting, because I want the quilt to be lightweight but to drape nicely as well. I'm thinking of going with lightweight poly or 80/20. Thank you for your suggestions!

Thinsulate by Thermore is a thin poly batting I"ve used some. Should drape nicely. comes in a gray bag.

Are you saying a quilt for a spread? If for spread only, you will not need any batting. Just the top and the bottom, and quilt as usual. A king quilt for a spread will be heavy.

wool batting drapes nicely.