Vast majority of domestic flights I've been on here have the lav at the back. Back row is the worst because of that and no recline. Amazes me how so few people bother to use the airport restroom before a 1-3 hour flight.
Basically the key to pleasant air travel is to be sufficiently wealthy to get those perks. Which is pretty much the case in any aspect of life, really.
Business class is the only way to travel, especially internationally. It's so superior it's hard to believe it's the same aircraft. It's literally the difference between arriving at your overseas destination refreshed, or a haggard zombie.