A burlap covered button seemed to be the perfect choice for the closure.
My only alteration is adding a fully lined zipper, and a couple pockets on the inside. Although I honestly can't remember if the pockets are originally included in the pattern or not. I do know the zippered pocket was my addition.
This was my first proper zippered pocket in a lining, so I needed some instructions. It worked up very nice and I am really glad I added it. Because of the large emptiness a big bag can create, I had to have something to keep lip balm from getting lost in the depths. And I do use that zippered pocket all the time.
Here's a picture from the subway in Paris, to give you an idea of its size and what it looks like full of stuff. :)
For our trip to New Zealand, I decided I wanted to have a zipper on the large opening, so the morning we left, I quick sewed in a zipper for added security. Not probably needed but I kind of like being able to secure all our odds and ends with more than just a button.