In Civ V, with the standard 4 self built cities: Basically build most building in all four cities : Unless this is a mod, you need 100% of several buildings in all cities to build the national wonders; which is a big part of why 4 self built cities work. The primary exception is military (you only need 1 military city if it's coastal / 2 (one land / other navy) if you started inland.
The slowest production city ends up getting a lot of these items rushed to avoid delaying the national wonders.
Usually you want all cities to be running all science slots (exception is a tiny city); the city has to have only tiles like 2f 0h 0c (or worse) to make enginners or merchants spots worth it, and even then only if you are confident you will remember to switch off it it BEFORE you accidentally spawn a GE or GM (GS much, much better)
Guilds: If going domination you should totally ignore them. You'll conquer enough great works produced by the AI as is and any extras just make it that much easier to accidentally trigger a conquest induced cultural victory.
For that matter, guilds are a low priority for science as well; just get enough to counter the AI. (Can also be totally ignored if you ensure you aren't the first to an ideology and then pick the popular one [normally order, but a human both being first and picking it seems to be the one thing that ensures the AI takes something else.])
With 4 self built cities you should be going full Tradition to start; which means you'll get Free monuments everywhere (except possibly the capital if you want the first few policies quicker; which ends up getting a free Amphitheater in the capital instead.)
Granary: It's also on the always build list : especally for 4 cities which is built around tall.
Shrine: Difficulty level dependent: If on King or below, it's always worth founding your own religion. On higher levels, it amounts to is there a pantheon that you could get a major faith bonus from with your start. There's also some advanced pantheon only (usually Sun God or Goddess of Hunt) possibilities (getting enough faith for a pantheon but that's it)
Market: Has a national wonder attached; so on the build everywhere list.
Armies: Should primarly be ranged based : Start with archers and upgrade to latest range unit. Add a few screen units as shields. Cats are for attacking an early city that's on a hill that also has walls; not needed against city on flat terrain. If the first target has one as a capital, the first war usually doesn't attempt to take their capital. Further down the tree siege weapons become more powerful (and also more needed against inland cities).
The horseman tactic was nerfed in a very early patch to Vanilla Civ V; it usually won't take cities (unless ranged units took down the walls first) but they are still good at running down enemy units in the open.
You don't need UUs to conquer the AI; so any civ will work for conquest. Instead look at the civs with economic bonuses.
By Turn 100 on standard speed:
1. Have completed the National College even if having gone Liberty and founded lots of other cities.
2. If you went Tradition have finished founding all the ones you are going to self found as well. (I guess it's possible with Liberty for a new city to still be worth it, but not for much longer)
If planning a war with Composite Bows + (your choice of screen unit) : Should either already be at war or in final preparations for it.
If instead planning a war with Crossbows: It's probably about time to start building additional ones as Composites along this line on top of the ones you had built earlier for defense; and save up the cash for the massive upgrade for upgrading several of them to crossbows the moment you get the tech and declaring war soon afterward.
If instead the planned war is later than that, it's still economic development phase; maybe throw in extra happiness structures compared to a peaceful plan so it's less likely that conquering cities will throw your empire into unhappiness.
I do note however that most players whose preferred victory type prefer epic speed. Turn 100 epic is around 67 standard which is
1. Have started construction of the national college if Tradition. (With BNW about the only way it's already complete is with Great Library. GL used to get Philosophy for free for a 1 city NC is the instant I win combo play.)
If instead Liberty, be close to starting construction of NC.
That's it; it's not much of a check point.
