Ok I figured this out, just now, after sleeping on it all night and spending yesterday doing no quilting, just a mountain of laundry.
I have determined that the blocks I just made will be backs to two new quilt tops.
I have 36 blocks, each is 16.5" square.
One quilt back will be 16 blocks, in four rows of four = 64" squarish
One quilt back with 20 blocks in five rows of four = 64 x 80" ish, with no leftover blocks.
So simple and obvious. Duh.
And not making a queen size bed quilt is smart, as I still have the chewing, licking, shedding dawggies that destroy things, sweetie pies that they are.