The Craftsy class from Leah Day on uses a Janome machine but you will find a lot of YouTube vids of hers too which is much cheaper. I started quilting a seven foot five inch square on a Designer 1 but the throat was too small and I swapped for a Pfaff Quilter which was just a little bigger throat. Even the biggest of quilts can be done - I just got sick of walking around my machine to pull the quilt through on the D1. I've since bought a Sweet 16 sit down, but didn't really need it - just wanted it lol It will come in very handy in years to come as I just adore quilting despite being a beginner. It's the best part of making a quilt I reckon now.

Support is everything when dealing with a large quilt. I throw mine over my shoulder, use a chair or an ironing board to support the weight of the quilt and only quilt a small portion at a time. For me, small is about a 12" square. Meandering is harder for me than quilting a design. With meandering you are constantly moving your quilt in all directions. If I use some type design....think wispy flower, curls, large feathers, I am not moving all the quilt so much. There are so many great long arm quilters on this board, that any picture they put up is very inspiring to me. I have learned a lot from them. I may not be the best one to help you, because I have never quilted one without some little puckering somewhere and sometimes, just downright pleats. I am going to try the washable glue method next time.