I like an 18" drop on all 3 sides, plus extra, maybe 6" to go under the pillows, so that's
60+18+18 = 96" wide and 80+18+6 = 104" long.
To be all blocks that would be 96/8 = 12 blocks wide and 13 blocks long.
Subtracting two blocks for borders: 10 blocks wide and 11 blocks long