Thank you, everyone!
I just finished laying out my quilt with the different border sizes and I think that the 5" border actually looks the best. The 4" wasn't wide enough, and the 6" seemed too wide.
I did look at the Fibonacci sequence and it makes sense to use the 5". The 'logs' and inner border are 1", my centers are 2", the border will be 5" and the blocks themselves are 8".