I have the same problem, so I am going to try quilt as you go, and see if that is any easier on my shoulders. Good luck.

The Singer 301 has a pretty big opening but I'm not sure exactly how big.

Janome 6500 has a 9 inch throat. It does not have the dual feed like the 6600 but believe me, it depends on the user as to whether you like Janome's dual feed or not (I don't). I have read that they have improved on the dual feed on the Horizon which does has the 11" throat. For the money, I think the Janome 6500 is probably the cheapest larger throat machine you will find, even among all the brands.

true that some don't like the accufeed. I happen to like it but on the 6600 you can sew with or without it.

There is a Janome that has a 14" throat, or so I have been told by a friend. In mho they all should be at least 20" lol

I have the horizon and a little confused about the accufeed feed. Does it replace the walking foot?? my machine did not come with a walking foot so my guess is yes. I do love the throat size and no need to roll the quilt I just munch it together. I still and very interested in finding or making a longarm frame for it. I think it would be a lot easier on my hands when doing free motion quilting.

I thought I remember learning that the bed of the machine was where the fabric lays and the throat plate was the metal piece the needle goes up and down in.
It is annoying not to have a big enough space. Some machines have a table you can attach and give you more area. Joann's has one with a plastic table attachment
simple quilter

Yes, search for "industrial machines". Also the Bailey Sewing Machine. I don't know anything about the Baily but see its advertisement.
The industrial machines have larger harp area.

These are all the domestic "larger than normal" sewing machines I know of:

Juki TL98 9"
Brother PQ 1500 9"
Babylock Quilters Dream Pro 9"
Pfaff Grand Hobby Quilter 9"
Janome 1600p 9"
Janome MC6500/6600 9"
Elna 7200/7300 9"
Viking/Husky Sapphire 10 or 11"
Janome Horizon 10 or 11"
Bernina 830? 10 or 11"
I believe Juki recently released or will soon release a longer than 9" throat/harp machine.

There are also stretched domestic machines. The Bailey Home Quilter is a stretched domestic machine. It comes in 13, 15 & I think, 17".

Wowquilts has a waiting list to stretch some of the above mentioned 9" straight stitch only machines into 18" machines. I haven't heard a single bad thing about the finished product other than the wait time to get it.

Looking at industrial machines is very confusing for me. Most seem to have the motor attached separately and they are so heavy; you wouldn't be moving them around your sewing room. They also run much, much faster than a domestic machine so they scare the crap out of me when they start up. And they take different needles and sometimes bobbins than domestic machines. If you have the space to setup one of the upholstery or sailcloth type industrial machines, you probably could use it to free motion quilt but having the extra space to leave the big honking thing is another story.

If you have a large quilt and a small harp on your machine, one way to get around this is to separate the batting into 3 strips. You machine quilt the center part of the quilt first. The side rolls up easily to fit under the arm because there is no batting in there. Once middle is quilted, you attach one of the side battings and quilt that.

Debra Wagner explained this technique in detail in one of her books. Now Marti Michell (sp?) has a book out on how to do it.