"Il libro sta sopra il giornale."
I think it is somehow different... "nel piatto" means "on the plate" as well as "sopra il giornale" means on (top of) the newspaper. But in the latter, plate is regarded as some kind of recipient. The newspaper can never (in its natural form) be regarded as a recipient for a physical object/animal/etc. So "nel" would not go that good with "giornale" unless (and now it's me wondering) you're referring to the "news" that are on the newspaper.