I also always spray baste. Luckily, I live in a community with a large "lodge" building, and can utilize one of the rooms and several long tables together when I am sandwiching a quilt. I've started doing it this way: Lay the batting out on the table first and get all of the wrinkles out of it. It helps sometimes to use the blue painters tape to secure the batting. I then, before spraying, put the backing on the batting, positioned just as I want it to be. Then I fold back 1/2 of the backing, spray about 1/3 of the exposed batting, and begin smoothing the backing onto the batting from the fold and towards the end of the batting. When the backing is covering the sprayed part, I spray another 1/3 and continue. If the quilt is wide I normally have a friend help me, and often use a long, smooth, lightweight piece of wooden trim to insure that the backing is moving down the quilt all at the same time. Once that half is complete I repeat the process on the other end. When the backing is securely, and flatly on the quilt batting I carefully turn the whole operation over so that the batting is on top, and repeat the process again with the quilt top. Since I started doing it this way the whole operation takes much less time, results in much less frustration, and normally results in a quilt sandwich free of wrinkles.