Ask to see samples of their work. You'll want to get an idea, if their quilting style is to your liking. Each LA Quilter has their own style and type of quilting they do best. Some prefer doing pantos. Some prefer freehand. Some are better at overall designs. And some are better at single block designs. Some do very well with feathers. Others do better with leaves. Not to mention the different fill types, stippling, McTavishing, pebbles, etc.
And ask for their suggestions on how they think your quilt might be quilted. Some designs and color combinations lend themselves to custom quilting and others are better off with a simpler overall design, because the heavier custom quilting would not show up.