People ask me "how large will your quilt be?" and I always answer that it will be what it will be. I don't sew to a size, rather, I let the blocks determine the layout/size and I adjust the borders to my whim. For me, it's more about proportion than final measurements.
A lot depends on the size of the recipient.
For an adult, I like it to be no less than 60" in length or it feels too small. If one wants to save fabric, the width can be equal to the backing fabric width (42-45").