AutomatedTeller said:
Usually, I end up trading tech for luxes, usually out of date or optional ones.
Yes, that's the key, isn't it? Absolutely
the key. And as izmirli posted above, he likes to aim for research in 4. That should give more than enough techs for trading.
Oh and a little tip for those that haven't figured it out. One should include 1 gpt from oneself to the AI in any tech-for-lux deal. In 20 turns' time they'll come along to complain that they don't think selling silk, etc, for 1 gpt is such a good thing, and at that point one offers them another tech plus 1 gpt. Keeps them locked into the (bilateral) deal, else it will just lapse.
Izmirli, You should also do this if you offer them straight cash for the lux, ie include 1 gpt there too. NB! If you have no techs to trade, it is much much better to offer the AIs cash than gpt payments. The AIs should always be paying
you the gpt, not the other way around.
When selling a tech, you need to visit all the AIs and watch very carefully what they can offer. The very first time you sell a tech, it will be at its most valuable, and in such cases you'll often find that the AI will offer both a luxury and gpt for it anyway. Indeed, its not unknown for such a "monopoly tech" to earn two luxuries and many 100s in gpt.
There are also occasions where you might need to send out workers to road the luxuries for the AI yourself. One other quirk: if you have 1 worker who will road in 1 turn and you add another, it will complete right then, and right then you set up the tech-trading deal. That's if the lux is very scarce and you're worried about losing the chance.
I'm no great expert but in my last Demigod trial (huge pangea, 16 civs), which was generally relatively peaceful, I got all 8 luxuries that way and kept them tied down throughout.
The other thing for people to keep in mind is that the gaps between towns should be 2-3 tiles, seldom 4 like the AI does it. Generally each city should average 12 usable tiles. Then as the game goes on, you do more and more irrigating (and railroading of the irrigation) in towns outside of the core. Cities with 2-3 tile gaps can easily support upwards of 16-20 pop, many of whom will be specialists, since there are no longer any free tiles to process. The presence of specialists does, in a way, suppress unhappiness, provided one has enough irrigation to feed them.
So if you're having a happiness problem with only some towns, and don't want to up the slider, then increasing irrigation and making some specialists might be an idea. Even an occasional entertainer should never be excluded if it's only one or two towns involved.
That having been said, I don't see anything whatsoever wrong with temples and cathedrals if one is following a builder strat and the circumstances allow one the luxury of building them. It all depends so very much on the goals chosen and the strategy adopted.
i have been always techically backwards till i found steam power 
my military was always weak and first iroquies attacked me and i played defensively later made peace with them.Later i trade with them and and i have 4 luxes.things have gone good when i traded luxes.But the problem was my military was still weak to them.Later Spain gave me spices and wanted technology from me ; they were polite.I traded my technology and 1 turn later they attacked me
but now i always respect my trades and treaties 
