One way to make it rectangular and look like it was supposed to be that way is to add a redwork border to the top or to the the top and bottom.

I like rectangular quilts as people who use them are usually longer than they are wide.
Simplist way is to make the top and bottom borders wider than the side borders.

Another technique is to 1) add the inner border, 2) make a checkerboard strip from 2 fabrics in the quilt, 3) add the checkerboard strip to the top and bottom, and 4) add the outside border.

Of course you can change it. I am another one who has only made rectangular quilts..

I've made a square into a rectangle by adding fancy borders to the top and bottom. I prefer rectangles.

I have found the old quilts are too square. They barely fit a full size mattress & queen or king, forget it. I'm making star blocks for oldest GS (graduates in 3 yrs) (good thing I got started early 'cause his brother & oldest GD the next yr, then another GD yr after, another GD 2 yrs later, another GD 2 yrs later & finally baby GD 2 yrs later). Just hope the Good Lord gives me continued health & no visits from Arthur. Anyway, am making oldest GS's very long & wider (than a twin) cause he's already 6'2", not even 16. My Mom has hand stitched blocks & is working on 15th of 16 14" ones now. When I use them I'll make it longer & future ones.

Hm..lots to think about, I am going to try and take a picture later and post it, hoping to anyways. Your suggestions all deserve merit and consideration.

I like square quilts on queen sized beds for design and function. As someone said, you can rotate to minimize wear and tear on the edges. I don't like to use quilts to cover the pillow, so that makes a square more useful.

Best way to add length is to add blocks not borders. I know you didn't want to hear that :)... I love square quilts for babies, but rectangle for all else.

For bed quilts, the size should take into account the size of the bed, the depth of the mattress, whether there is a footboard, whether the user wants a pillow tuck... For king or queen, this usually means a quilt that is close to square, or even wider than it is long. For a twin or bunk bed, rectangular is better. A full bed could go either way. For a throw that I snuggle with on the couch, I prefer square. So... I guess my preference is with a square quilt. Most quilt designs work out better with a square too.

I always make large bed quilts, king, queen and double square. Generally I make lap quilts and most baby quilts rectangular with the exception of baby floor quilts or quilts to cary babies in. (kind of like recieving blankets) I also prefer utility quilts for in the car, park or on the beach a large square like 65x65. I think it sound like your quilt does not look complete to you eventhough it is done. I have added strips to the top and bottom of quilts in order to achieve the size I wanted, like for extra long twin bed quilts, but never just for the look of it. To me it generally takes away from the look.