I have spray basted over 150 quilts, either my own or helped with my friends. We have a super easy technique. Cover my king bed with a big flannel sheet, put batting down and arrange backing on that, fold back half of backing, spray batting and smooth backing back down. Fold back other half, spray and smooth. Flip it over so batting is on top, arrange quilt top and continue the fold back, spraying, smooth technique. Walk away and leave it for 30 minutes or so and it's ready to go.
I was using June Taylor with great results, then they changed to a different formula and it was HORRIBLE. After emailing them they were great and have now changed their formula again. The new formula is in the new style can that tapers down on the top with a small cap but be sure that it says "Improved Formula" in dark pink or red on the front. The formula is pretty much the same as 505 and Dritz and I really like it. I don't like the Sullivan's in the pink can though.