I’m really looking forward to an upcoming print feature and print-to-pdf or save-to-pdf feature. I’m hoping that one of the options for printing will be to define a custom footer and/or header.
Some of the critical things for footers besides the very obvious “Page # of #” include branding, attribution, “Confidential” and similar labeling, URL, copyright, address/contact information.
Headers are also important for the same reason, and the ability to include an image (e.g. a logo for branding) would be a nice bonus. A separate header is not as critical as the footer IF you allow the user to choose a number of rows at the top to be printed on every page … but that doesn’t really allow you to use automated page numbering in a header.
One of the things Google Sheets lacks is the ability to choose the font color for footers. For example, you’d want to choose red for a “Confidential” notice or gray for text when you don’t want to draw too much attention.
I’ve always liked how Excel and GS give you the option to enter footer info into a left, center, or right section.
While I’m adding to my wish list for print settings … the ability to define custom margins is also very important (I’d take a Standard/Narrow option for margins if custom is not possible, where narrow is usually around 0.35" to 0.4", 0.9 to 1.0 cm, though most good printers can print more narrow than that). The ability to scale the print area to fit on a particular number of pages is also critical for spreadsheets.