I love these blocks! Not sure about sashing....I'd have to audition some fabric to see. I kind of like them as they are, next to one another. As for borders, I'd go with a solid narrow inner border, maybe in that turquoise or yellow, and the red bandana print as the outer. But with these fabrics and choices, I don't think you can go wrong, whatever you decide to do. This is going to look great!