In the four examples shown below, you will see four "treatments" with respect to the positioning of headers and page numbers in four different books. Note also the difference in type style based on fiction vs. non-fiction vs children's books and the appearance of "ornaments," and drop caps in the fiction example.
NON-FICTION, Headers and Page Numbers Outside Top
FICTION, Headers and Page Numbers Center Bottom
REFERENCE - Headers and Page Numbers Outside Top and Bottom
CHILDREN'S BOOK - No page numbers or headers on 2-page spread