STYLE -- SELECTING YOUR CS PAPERBACK FONTS
Unlike Kindle, CreateSpace can duplicate any font you choose, so you have much more creativity in the way your book will present. However, you'll upload the final version of your book in the form of a PDF, which will require fonts to be 'embedded' in the manuscript. Although the CreateSpace guidelines do address the matter of embedding fonts, to me it seemed complicated and, ultimately, unnecessary.
TRUE TYPE FONTS
You don't have to worry about embedding fonts in your PDF if the fonts you choose are 'True Type' fonts. And the large selection of True Type fonts should keep almost every writer happy.
How do you know if the font you choose is a True Type Font?
Once you've chosen the fonts for your text, chapter headings, front pages, etc., create a sample page using each of these fonts. Then save this page as a PDF. With the PDF document open, Choose FILE - PROPERTIES. Then click on the FONTS tab. A window will open showing all the fonts in your document, along with accompanying information on each font. If the information next to your font says 'embedded' or 'embedded subset' your font does not need embedding. If that information is missing, then you must embed that font yourself. If you don't already know how to do that, my suggestion is: find an embedded font you can live with.
My font choices included Marker Felt, Copperplate, Lucida Grande, Franklin Gothic, Corbel, and Chalkboard; all True Type fonts.
Changing a font in a manuscript can sometimes lead to losing certain formatting, especially italics, bold, underlining, etc. Test this on a sample page to avoid losing your mind.
The old myth about serif fonts being easier to read than sans-serif fonts has been debunked. Simply choose a font you find pleasing and readable. Font size for the body of your book is always 12.
YOU'RE GETTING THERE
Once you've chosen and vetted your fonts, make the appropriate font changes to your manuscript. Then copy and paste the manuscript into your 6 x 9 'publish' template.