I find it much easier to quilt standing up -- easier on my shoulders and back, so I can quilt for much longer periods of time. To do this, I place my sewing machine on top of my cutting table (which is at about belly button level) and surround the machine with a styrofoam table my dh made.
Directions for the table are here:
http://www.youtube.com/watch?v=g14govA4pIM
http://www.youtube.com/watch?v=yAS25...eature=channel
For me, at least, I don't think a frame for my domestic sewing machine would help as much as this setup does. I can see how a frame for a midarm or longarm would help, though!