Thanks so much for the quilt-back explanations, guys! I never would have thought of how the quilting seams need to line up. But I do have a follow-up question - it feels like a lot of quilts these days are quilted freehand, with those loopy random swirls and whirls. That kind of pattern doesn't really need a plain back, does it? Anyway, in my case, I probably should have mentioned that I'm not planning to quilt this thing - the inside is going to be an old down comforter and I'm guessing those feathers would make for way more broken needles than I want to deal with (how many do I want to deal with, you ask? Um, zero.). So instead I'm taking the lazy coward's way out - I'm going to tie this baby.
Oh, and no, I totally didn't prewash - again, for laziness reasons. Last time I prewashed, the fabric went totally out of square and added an extra layer of annoying to the cutting out. I like to take the easy way out and use the fabric hems as guides. Also, since a lot of these flannels are polka dotted, I was basically cutting along the dotted lines much of the time, rather than laboriously measuring everything out. In my defense, I am still somewhat traumatized by the amount of time this thing took.