Here are my borders for round 2:
I immediately thought of log cabins as a representation of squares. The large ones are 3-inches–I described the stamped foundation on my blog, here: Log Cabin Squares. For the smaller white ones, I used the same foundations, but didn't add the last round of logs. They are 2-inches. The letters in the word border are based on squares (and have quite a few squares in their construction.) The word row is approximately 4 1/2 inches tall.
Here's how the borders look, sewn in place.
The piece is still, definitely rather L-shaped. I hope to remedy that with round 3.
Because I am always curious about how big the other LibRR's are, I measured mine for you. It's approximately 26 inches tall and 28 inches wide at the bottom edge.
Like Sue R., a theme has emerged for me . . . though it may not yet be obvious to anyone else ;-)