For a GP farm aiming to get scientists, should I avoid getting any wonders that give GP points that aren't scientists in a GP farm city and just run scientist specialists for awhile? Also, do I avoid building too many wonders in my capital to avoid diluting my GP farms effect, or can they both be successful farms? I love matching Elizabeth with Pacifism and using the Parthenon as well. Should I build The Parthenon in a production city like my capital or should I try to use my GP city to get it?
If you build Wonders of the non-preferred type, you can expect slightly fewer GPs of the preferred type. Adding 10% pollution, for example, means you'll get about 5% more total GPs (because as noted above it's second-order, or third in the very long run), but 10% of your GPs will be the non-preferred type, so a 5% reduction of the preferred type.
I practice I don't really care about an occasional non-preferred GP except for Great Artists. They're good for starting a Golden Age, and, um ... well if you're going for cultural, they're good then, too. But overall their value is vastly less than any other type. So keep the Parthenon out of your GP farm if at all possible.
How to use GPs? It depends, of course, but most often for me:
GE -- early on grab the Pyramids. If you think you're in danger of losing the Great Library, rush that. Otherwise, save him for Mining Inc. It's often hard to secure a GE "on demand" later on. And I mostly play for late game domination wins, which makes Mining Inc ridiculously good. If you don't expect to pursue late wars, then settling him is fine.
GM -- early, settle him. You'd like to land him in your eventual Wall St city, but sometimes the extra food is more important, if it'll let your HE city work an extra mine for example. Late game, trade missions become strong once they're up over 1500-2000 gold or so. Run the slider at 100% for a very long time, or mass upgrade some CR3 maces to rifles.
GA -- golden age. But try to avoid them if you can.
GP -- mostly settle. I don't normally have a religion that I'm pushing, unless I've captured a holy city. It should be pretty clear when shrining is better vs. settling.
GSci -- the first two 'bulb Philosophy and build an Academy, often in the capital to benefit from Bureaucracy. Then often one 'bulb for Education, and either settle or build more Academies with the rest. Representation obviously favors settling, but I favor cottage economies, so I've probably got at least 3 or 4 cities that want Academies reasonably soon.
GSpy -- usually infiltrate and steal techs. I haven't yet tried a dedicated spy economy, though I keep meaning too....
peace,
lilnev