Funny you should post this, I was *just* experimenting with this issue this weekend. I don't want to make a heavy quilt for someone in AZ, so I thought flannel would be the thing. I too, have to piece them together, and I found that even with a pressed open seam I'm feeling the bulk of the seam. I wonder if the suggestion of a fusible seam tape would be workable...it also happens the quilt has a good deal of white in it, hoping it won't show. Ack!