Spray basting is much less time consuming than fusible batting, especially for larger projects. 505 fabric spray adhesive is a good way to go. Very quick and easy.
Lay out your quilt on the floor (backing, batting, top). Then tuck some newspaper underneath, around the edges. Lift the top and batting up and fold it back, half way. Spray the backing, then fold the batting down onto it and smooth it out. Spray the batting, then fold the top down onto it and smooth it out. Then repeat for the other side.
I sew all the way around the outer edge with a basting stitch to hold the layers together. Then I'll put a few safety pins in to help hold it together.