This cross section image shows the locations of the two rest areas on the 787:
https://i.pinimg.com/originals/b2/de/d4/b2ded457430d5313d223...
(Number 9 and 44.)
https://i.pinimg.com/originals/b2/de/d4/b2ded457430d5313d223...
(Number 9 and 44.)
The emergency exit row is also great for cheap legroom. But sometimes the seats don't recline