I started off washing all my fabrics. I did a couple of block of the months where I didn't wash the fabric and I really couldn't tell much difference after they were finished.
The batting you choose has a whole lot more to do with the look of the finished quilt than washing or not washing the fabric.
I haven't found many fabrics that actually bleed. Most of what people think of as bleeding fabric is just the excess dye washing out. Toss in a color catcher in the first wash and you shouldn't have a problem.