Brown is really a mix of a basic color and it`s complimentary color....you can tell which by finiding the tint in ur brown....redish and or green.....orange and or blue......purple and or yellow.....I do think blue would be nice and as others have also said maybe a green.....but just sewing the blocks together and making a nice border around would work too...I would even consider putting a sashing using the light beige you have in the middle of your blocks then adding borders....that`s a lot of options...lol