The layout and type you use should not even be noticed. The goals of good layout/typesetting is to use signals to let the reader know what language structure they are currently in, such as a heading, paragraph, sentence or quote.
Your readers have been conditioned from a very young age to recognize these signals unconsciously so they can understand what a section of text is for without having to consciously figure it out. For them it is familiar, comforting, and expected. That is the form. What the words say is, for the most part, is completely unrelated. Confuse them with a plot twist, not some odd treatment of the text. Bad layout and type treatments will force them out of the world you have created back to a reader trying to interpret what a screen or paper page is trying to convey.
This presentation will explore the proven standards that have been used for centuries, and how to adapt them to your own books.
Below is the presentation that was given (in various formats).