Great quilt! Congratulations!
I'd do as others have suggested and keep it simple. My Brother 450Q has a serpentine stitch, which is a wavy line, that I use a lot when quilting. It's a little more decorative than straight line quilt and goes fast. Or there's always stitch in the ditch, which, frankly, I find difficult....keeping the stitch (needle) in the ditch, lol.
And yes, use a walking foot. Good luck, whatever you choose to do!