This quilt is so lovely and cool all on it's own. I think you could get away with no borders, just a binding and consider it done! On the other hand, I don't think a border would be bad either, it really could go either way. However, if you are going to go with a border, I don't think it should be too busy. Your quilt is pretty busy in both design and fabrics. That is what you want to shine. I think I would do a solid border, not super wide, just to frame it as it were, and then either a contrasting outer border or just binding that picks up on the colors inside. Audition some fabrics before you make your choice. Truly, I vote no border as it really is lovely the way it is and makes a statement all it's own.