obsolete
Deity
Guess thats your strat, and you're bias against cottages, but they aren't synonymous with lightbulbing. I NEVER NEVER NEVER waste GP on lightbulbing, but I do find cottages extreamly powerfull with a financial civ early on. I suppose if you decide to keep representation during the late game that a farm enables you to run another scientist giving +6 beakers, but still, 8 commerce from that town before modifiers is about +24 beakers not to mention that +1h with US (which after a certain point far outwieghs rep, unless theres nothing to worthwhile to build)
I'm also surprised you like building Oxford/Ironworks in your capital not getting national epic, yes NE gives that +1 Ga pollution, but I rarely have artists arrive my capital when I JUST build NE in it and save the parth, broadway, Rock'n roll, taj'mahal, etc for my other other cities. +100% GP rate is HUGE early in the game, especially with all those wonders, its like having 18 turns for a GP cut down to 12 turns (with the parthenon). If I do end up having a few Great Artists, I just burn em on golden ages (esp since you can start your 1st golden age with just 1 GP). You don't get Ironworks/oxford till later on (when you have a few other decent cities to build one of em in anyways) and a bonus earlier in the game >>> then later in the game. I dont use national part often (the game is already won or lost by the time it comes availible, and I usually cottage down all the forests anyways), and the whole concept of a GP farm outside your captial is forgien to me, since I wonderspam my captial from the getgo.
Oxford is pretty optimal when coupled with IronWorks in a SSE/WE system. You are hitting two birds with one stone in a very big way here. I used to couple the NE with the IW here back in some older games, but have resorted to Oxford instead. The G*s that arrive are a little less, but you get a large boost science wise here. The only trick, is to make sure you get at least SIX cities.
Not many believe just yet, but I guarantee you that no more is needed for beating deity with this strategy.
As for the National Park, I think it's one of the most over-rated national wonders too. However, in this game I was actually able to use it perfectly with the secondary capital. Coupling that with NE was optimal. Usually I only have one GP farm, but I think with BtS I will end up often having two of them now. There is a small G* penalty for it though.