I like to use thin fleece (on the bolt in the batting area) and flannel.. however flannel always seems more expensive than the thin fleece.
I have also used the thick muslin for batting as well.
Having said that, I'm not fond of high loft quilts at all so I try to go as thin as I can.
I don't go without as you can see through them if you don't and I don't like to see the backing on the front - especially for table runners and place mats as I try to make them double sided for double duty ;)