I made a bottom-of-the-bed runner this past Summer. It is the length of the bed plus some drop. It also fits on the back of the family room devan to add color.
I didn't get any criticism. from the judge as to length. There were others entered, and they seemed to be the length of the bed also
To be hones, mine was the start of a quilt as you go quilt that I got tired of working on!
Mariah