OOC:
I hoped you wouldn't get into this because you're so knowledgeable!!!
You cannot hide from the truth.
Yes, unhappy citizens do drain resources, but in my games, I usually switch to HR or hook up happiness resources quickly enough for whipping to disadvantage me. For this reason, I usually do not whip unless:
1) I'm in war or something and need units fast
2) I'm in a race for a wonder
3) All of the new tiles I would be able to work with an extra pop are really crappy and I am doing a no specialist variant or something.
We are quite some time from Hereditary Rule, so that doesn't help us; the only happiness resources we have the technology to connect are in Iberia, where we have no Workers, and currently do not have a Galley available to transport them there. Also, that one Barbarian would kill them or pillage the improvements if we can't deal with it.
Strange as it may sound, whipping can help a city grow
faster, even if there are improved tiles to grow into. The best example is whipping a Granary as soon as you are able to, because the Granary will double the subsequent growth of the city. Also, the greater the food bonuses available to the city, the less the lost population matters because they will all grow back that much more quickly. I generally whip early and often, usually infrastructure projects. That way, the benefits accrue much more quickly.
IC: AND WE SHOULDN'T ADOPT SLAVERY BECAUSE IT'S UNFAIR!!! I believe that all living things are equal. In what way is a slave's life any less useful than a master's life?
EDIT: And we don't have very many cities that are above their happy cap, anyway.
You are quite correct. A slave's life is no less useful than the master's (although, remember, I am not proposing hereditary slavery or any permanent slave "caste," so I do not see any "masters" per se), but a slave's life is useful in a different way than that of law-abiding citizens. Rather than spend years of their lives locked up, sitting in a cell, they can provide cheap manual labor when the need is great. If a few of them perish in the process, well, I have already said that they will have given their lives to a greater cause.
And, as I explained above, waiting until a city is near or above the Happy Cap is not one of the prerequisites for deciding when to whip. I usually try to time it for maximum overflow, so that each life lost provides maximum benefit. See? I can be generous, too.