It looks great "as is". If you need it bigger, add more of the same blocks. If you don't have more of the same fabrics... use different fabrics with similiar tones and mix em up.
If you want to audition different sashings... just put the fabric of choice behind the blocks and space the blocks one or two inches apart. Stand across the room and look at it... you'll know if one catches your eye. Try different colors, before you make any cuts.
I have a program called Quilt Pro. I like it much better than Electric Quilt. I use it to audition different blocks with and without sashing, and change colors with a click.
Good Luck,
sewdarnbusy