battings vary greatly from needing to be quilted every 2" up to every 10-12" so it depends on the batting first off, if you want to do some real heavy quilting use the 2" stuff; if your batting says it can be quilted up to 10" apart that pretty much gives you lots of 'play-room' you can decide what you want to do and decide on proportion to get it balanced around the quilt without worrying too much about not getting it enough (unless you just outlined 12" blocks..) so start with your batting requirements then choose a design you like that fits in that requirement.