courthouses are totally worth it if you can afford the short term unhappiness. 5 gold is easily offset by most cities. Thats only a few tradeposts...
I like to only have 2-3 MAX at a time on prince. The rest I puppet (3-4). I like to wait till city is out of resistance (angry red fist) and then pop a golden age and micro for max production.
Unhappiness isn't the end of the world, you still tech up as normal but the loss of production at very unhappy can suck for courthouse building.
Course, this is all done when war is over - other guy begs peace.
Its all very situational... if in doubt, bite off small bits at a time and don't neglect your income
Setting your main cities to avoid growth is often a good idea when wrapping up a war.
one more thing, i find that relying on traded luxuries for happy is risky business. It can buy you time though.
Sorry if sounding jibberish, jsut got done with a 18 hour civ stretch, need sleep