Well, I usually use Letter size (8.5x11) for songbooks with either LARGE 18+ pt fonts or 12 pt with staff music OR for just words using 10 or 12 pt fonts, I use 1/2 of the Letter size (8.5x11 cut in half) put into appropriate 3 ring binders.

BTW - Has anyone knowledge of a source of those binders that self-prop up. They have a fold about half way and that slants the book on a table to read. I've seen a handbell choir using such a binder (smallish) but I haven't seen it in the letter size. Any thoughts?