If you're like me... you're a digital reader and probably don't think about print that much. The bottom line is that the only dimensions that matter in terms of pricing is the thickness. A book can be too big because it's conversely too small in terms of measurement. Don't go with the smallest size.
Createspace doesn't exactly tell you everything when you're choosing the physical dimensions of your book. It's a bit counter intuitive.
This is a good online tool for estimating page count: http://wordstopages.com/
Also.... follow me on Youtube. Because I may do more of these posts.
Mike bode is the author of The Queen of Lies, the first installment in the ongoing series, Architects of the Grand Design. His next book comes out October. Sign up for the mailing list for more info. You can find him on Facebook, Twitter and Pinterest . (You can also follow him on Goodreads and even Amazon)