On paper (or should I say, on screen) my first reaction would be #2. For the work of sashing, I don't think you'd accomplish anything if you are doing strictly black and white. Now if you're doing an assortment of B+W and B+W prints, then that could be different.
However .... and JIMHO ... get the blocks made before you make your decision re sashes/borders.
Once you have the real thing in front of you, you can get a very real feel as to what borders are needed, and how wide.
There is no need to decide now (again JIMHO) !!!