I would shy away from satin stitching, you may not like the way it looks on the back of the quilt. And you will have a lot of quilt wrestling to do as you turn the quilt round and round sewing the edges :D:D:D
Depending on how you have quilted it, machine stitching the appliques down may add to and be complimentary to the previous quilting. Depending on the backing and color of thread used, it may not show much at all either :D again though, it means spinning the quilt around to sew them down.
Leaving the edges unfinished, the raggy look is very popular with some, you would only need to straight stitch inside of the appliques edges.
Turning the pieces under and handstitching would give the most finished of looks. The stitches wouldn't show on the back of the quilt. There are many ways of accomplishing this look.