Since you've resurrected this, and there's plenty of 100k ideas by others here, I hope this isn't clutter.
Remember that you want Gunpowder and saltpeter so that you can use muskets for short-rushing.
I haven't played a 100k anywhere other than Chieftain, but even there I realized that I could whip my towns into unhappiness (I think with 4 or 5 luxuries) so that they can't grow due to unhappiness even with a very high luxury slider rate. *If* you go with the ToA, and *if* you can get an extra SGL for The Oracle or The Sistine Chapel, how valuable are they? Whipping settlers, and everything else would I think come as easier to execute. Utility of an extra SGL suggests Sumeria or Babylon as potentially more powerful than the HoF tables lead us to believe.
Also, how valuable is getting two SGLs (both Pyramids and ToA for one-turn's production) instead of just one in the ancient age, or one SGL instead of none?
Not clutter - I am 120 turns in to a Tiny chief - won't break 200 turns, probably won't break 210. but a good warm up.
One SGL in the ancient age is essential - for pyramids. Any thing else is a restart.
The ToA can be handbuilt, but costs 30 to 40 turns. at that time you might have 15 to 20 cities so that will cost you about 1200 to 1500 culture directly, plus the opportunity cost of what else you can do with 500 shields. That is probably equivalent to 5 settlers by the end of the period, which might turn into 10 to 15 by the end of the game so that is probably the same again. Thats probably 2-3 turns on a tiny map, 1-2 on a huge one.
Scientific will generate more SGL's than others, but that just means you have to be patient with the non scientific ones. Yes you can whip yourself into oblivion, but with an agri civ, you just change your only citizen into a taxman, and build workers. You have 3$PT, and a 10 turn worker pump, whereas a non agri civ only has the 3$PT. That and the fact that Agri irrigated desert is 2F1S makes a whip economy much easier to manage (you never want any corrupt city to be working a 1F tile - 2F you don't mind either way, and the 3+F need to be worked constantly.
Oracle isn't really worth it - 1

won't last long under the whip. Sistines is worth going for on the other hand (at least on larger games) as happiness isn't usually an issue until you have whiped the cathedral. probably won't save you a whole turn though.
Other things that are more important and will save more than a couple of turns
a) a second or third settler factory
b) the time taken for the settlers to reach the new land
c) not getting sneak attacked
There may be a secondary rush path using settler and aqueduct and knight for dry cities. 10 shield in the bin to start while growing, 10 shields at the end while growing.