i forgot to mention ...
i backed this one using fleece from WalMart. the first time i backed a cotton top with fleece, i didn't put anything in between. it went well enough, but i got a bit more stretch and pucker on the top than i had hoped.
this time, i put a layer of thin cotton batting in between. the cotton top stuck nicely to the batting and the batting stuck nicely to the fleece. i didn't need to spray-baste. i was able to get by with just pins.
i assume cotton flannel would work just as well as batting. i just don't happen to have any.