I just signed up for a series of quilting classes starting with Stitch-in-the-ditch and ending with free motion thread play. My machine is a Babylock Espire and it has a respectable throat area. I also have a Pfaff Grandquilter which is a mechanical straightstitch machine geared toward quilting.
Are you looking for a mid-arm or long-arm, or do you want to learn how to quilt with a regular sewing machine?