I'm working this out myself, I tend to go for long conquest only games so I get the chance to build a large empire and fight some huge battles. I imagine taking the policy and wonder that reduces unhappy for city plants to zero is key. Along with some per-city happy policies like the honor one or the ...liberty? getting my policies confused. Anyway, with those policies, wonder and just one of the three standard happy buildings you are looking at a size 8 city that does not touch the global happy pool (meaning luxuries, trades, wonders, etc). I think the other two standard happy buildings will let you go to size 15 without touching the global. Then you have some happy buildings which are situational like the circus, but will probably average out to another 1 to 2 happy empire wide. So you should be able to get every city to around 17 to 18 size without touching empire wide happy generators.
In addition, it would seem that ICS style of play really augments this because several cities could swap resources around like horses to build the circus. I haven't tested, but I don't think once the building has been built that you lose it's benefit if you lose the resource that let you build it. If you do, no worries you can still get a 17 or so size city and maintain an enormous happy surplus. the caveat is you need to get to those policies, wonders and technologies to unlock the additional happiness before you spiral out of control and shut down. As long as you plan it out and hit the important points on your schedule you should be able to support large cities while maintaining a large happy surplus.
If you want an ICS style of play or hybrid, I'm finding that growing a little at first and nabbing 3 policies before really exploding helps. I'm grabbing the +1hammer per city policy as quickly with my first 3 picks, and while doing that making sure my tech gets me to Colosseum's so that even with early, small cities I can get one built in 25 to 30 turns in a bad case. Other things I look for are areas of high food that I can share with new cities. Get one to size 3 asap and switch off with another city to bring it up. Usually can nab at least one hammer square to help the early production as well as keeping me competitive in science.
Currently, I'm still screwing up as I'm trying to find my balance, but they are fun learning experiences. My current dilemma (i'm playing Songhai to make it easier for me) is trying to decide if I want to spend my first batches of money on expansion, happiness or military.
My current thought is to try and kill two birds and save up my money to do a 500 or 750 buy in to a culture city-state that has a luxury available. Would help me get my still get some policies despite a bit of expansion and would tide me over on some happiness until I can get productive enough to start pumping out some buildings. The trade network seems to be completely adequate to keep my afloat monetarily with the buildings.
My real problem is when I tried this on diety, I kept losing my city-states to the other civs, so i'm wondering if I should just invest the first 650 or so into putting down my mud pyramid mosque insteaad. Not as much, slows my expansion because i'm down some initial happiness, but is much safer and expands my city area quicker. bah, still so many options to look at!!!
Currently I'm looking at trying to go with max range city placement, huge populations and rely on specialist policies to keep my happiness under control. Not sure how it will do,or how high the cities can go this way, but it's going to be fun testing it
