I am looking to purchase a sit down long arm machine, because I don't have room for a frame but love FMQ. I have a regular sized machine for piecing but it is a struggle to FMQ a large quilt. Any ideas?

I can think of 3 models off the top of my head:

HQ Sixteen - 16" arm
Tin Lizzie Queen - 18" arm
APQS George - 20" arm, I believe.

here's the queen quilter 18 that has gotten some good reviews in the market.

http://www.sewingmachinesplus.com/tinlizzie-qqsd.php

just remember you'll still have to deal with the weight of moving a large quilt around and all the drag that comes with it.

i strongly suggest you give this a test run with your "typical" large quilt and see if you have better results before you purchase.

I was so tempted to buy this when I saw it at the quilt show. Seems to me it meets all your requirements.

Easy Quilter 3

easyquilter.com

Check out the Sunshine 16 at www.pennywinkleranch.com. For the money, I thin it is a good deal. Tried it at Knoxville show last year and was very impressed with how smoothly the movement was.

My second choice would be the HQ 16.