When I teach hand quilting, I recommend a hoop between 10-14 inches in diameter. Anything larger is usally too large, unless you have realllllyyyy long arms. Most quilters these days can only stitch comfortably in one direction, and constantly rotate their hoops so that they can work in comfort. Those of us who learned to quilt on large floor frames know that it is possible, with practice, to quilt in all directions, but I usually leave those exercises for later classes.
But you don't need a big hoop to quilt big quilts. I've done everything up to queens on my 12" one.
'Winds of inspiration. . .'
Quilt Canada 2010
Telus Convention Centre, Calgary, AB
April 26 - May 1 2010