Re: Spiritual
In playing
without the Spiritual trait, I've found that nonSpiritual Civs have to spend 2 turns minimum on anarchy in the late game. That's an incredible disincentive for any Civic switching.
Reasons for late-game Civic switching are for running Representation/Universal Suffrage in alternate for the building buy, using Vassalage/Theocracy to increase the XP for a spate of unit building and/or drafting, switching to Nationhood momentarily for massive drafts, and switching between Free Religion/Pacifism for wartime/peacetime situations.
If you have lots of forests, running Environmentalism to offset war weariness (on top of running Nationhood for the +2
from Barracks) can put off an urgent stop to a profitable war.
Late in the game, no civ without Spiritual can afford to juggle such Civics profitably.
Also, Spiral Minaret gives +2 gold per State Religion Building.
Re: Aggressive
The most effective way to use the extra promotion is to build a barracks to get a second promotion right off the bat. Cover and Shock promotions are popular in the earlier ages, and Pinch is often key in the latter ages.
Aggressive has an obscure economic advantage. You can spam the cheap Barracks in all your cities in order to benefit from the 2 happy faces from a Nationhood Civic. This can actually be useful if you've already got plenty of health and are hurting for the happy luxuries. The Nationhood Civic is available through Nationalism, but can also be used if you managed to leverage the Pyramids (from an Industrious trait).
Aside from the obvious, Aggressive Civs benefit the most from Drafting, since the first promotion is free. That means that they'll be able to draft large quantities of level 2 units even with just a Barracks and the Pentagon or any one of the +2 XP Civics. In contrast, even a Charismatic Civic needs to leverage +8 to draft a level 2 unit - not somethng easy to do across your entire civ.
Japan's drafted Gunpowder units are particularly scary. With just Theocracy and Barracks (an elementary setup), Tokugawa can easily draft tens of Riflemen all with City Garrison I, Drill I, Combat I, and one other promotion, usually Pinch. That's a match for even Churchill's Redcoats.
Re: Expansive
For me, Expansive is easily one of the most powerful traits in the game, trumping Financial. The trick to using Expansive can be most easily seen with Mehmed, who's got Health and Happies by the ton. Mehmed's health and happy limits are ludicrously high, so you can afford to grow your cities to size 20, even in the late Medieval period.
Once you've played that, you begin to find ways to make happies to leverage your Health benefits. The usual way is to get lots of luxury resources ASAP, or to found or borrow as many religions as you can get your hands on. Then you supplement that with unit happies from Hereditary Rule.
Whipping actually runs counter to Expansive play, since you'll never see the benefit of your Expansive trait if you're not constantly running your cities into the sewer - and you'll only do that if you run very large cities. Granaries help with this goal both by increasing your health limits and by increasing your city's rate of growth. At the limits of health, Expansive is worth +2 food per city. This can mean about +10 turns more of 1 additional population production, more if your city is growing when it shouldn't be.
Expansive Civs like to have the happies to be strong. They want religion, they want spices, they want incense. Just think "Spain" and you're probably right on on the money.
If you can't swing that, you might want to go to Drama for the early Theatres for happy faces. Diverting money into culture to grow bigger cities faster actually makes fiscal sense - you can always scale back the culture slider and rake in the benefits of your fast growth, while putting on the brakes.
The Hanging Gardens is actually not soemthing I would recommend, since you usually have other priorities to worry about. Rather than pursuing that, I might recommend building Cathedrals after Music. If you're Industrious, you might want to build the Pyramids for Nationhood and mass Barracks. Or you could be building more units to build up the happies with HR. I would more recommend Notre Dame, since that wonder gives you the happies that make the health boost so useful.
University of Sankore would also tie in well, since you usually have Cathedrals and Temples all over the place.
Contrary to what you say, there
aren't all that many ways to increase health. In fact, as the game wears on, more and more sources of unhealth begin to pile up.
Granaries, of course, only continue to build more health as the game progresses, since you typically acquire the other resources that increase health through granaries, or manage to capture the resources yourself. In addition, the Harbor (also half price) can allow you to build truly massive coastal cities very quickly, with the attending massive trade route bonuses.
In the modern ear, health can be a continuing problem, as you build factories, coal plants, forges, and airports, not to mention bigger and bigger cities. Expansive Civs get to big cities faster and continue to grow where lesser civ's cities stop. At that stage in the game, there are so many ways to make happies that it's rarely an issue. Aside from the resources themselves, Cathedrals boost incense, forges boost gems, silver, and gold, and markets also boost their share of the resources. On top of that, you can create threatres and coliseums with relative ease, giving you as much as 3 happies with just a 20% slider modification. Multiple temples provide one happy each, and Free Religion provides one happy more on top of that for each temple.
Health is not so easy to come by, and that makes health the second most common city size limiting factor in the late game, after tile quality.
In like manner, I also consider Charismatic superior to Financial. Not every city or even every city tile can benefit from financial. EVERY city will eventually benefit from Charismatic by one population, and this limit will usually be strained to the limit throughout the remainder of the game. Obvious exceptions are the Globe Theatre city, new cities, and cities that are for some reason purposefully small, but these are corner cases.
In terms of war, Charismatic is possibly the best trait for fielding in elite units.
Upgrading units plays to Charismatic, as 10XP isn't nearly as disastrous for it as it is for other Civs, but its real benefit is in fielding in highly decorated units right from the get-go.
West Point is a key wonder for mid to late game warmongering. It's absolutely divine in a bay cty (a coastal city that doesn't have a lot of ocean sqaures), since it'll upgrade your Battleships as well!
I like to make a goal for myself with Charismatic: to have a level 6 unit before Military Tradition, but if you have to leverage the West Point with a GG, it's no biggie.
Aside from the obvious synergies with Charismatic, I aim for West Point in order to get a very specific promotion: Blitz. Blitz is a level 5Gunship/Mounted/Armored promotion. That means 4 promotions, or 13 XP for Charismatic. You'll need Barracks (+3XP), Stable (+2XP), West Point (+4XP), Military Instructor (+2 XP) and either Theocracy (+2XP) or Vassalage (+2 XP).
That's 13 XP, and that allows you to produce a Combat 3 Blitz Cavalry fresh from the Academy. If you can swing for another GG, you can settle it in the same city and keep on producing Combat 3 Blitz Gunships straight into the Modern Age.
You could do the same with a nonCharismatic Civ, of course, but you'll need to be locked into BOTH Theocracy and Vassalage, or have 1 extra Military Instructor (which could have been a Warlord, and may not be available just yet). Moreover, the XP your Blitz Cavalry will accure using their multiple attacks will most quickly translate into more promotions with a Charismatic leader.
What to do with Blitz Cavalry? Why kill multiple weakened units in a stack of course! With the right promotions and the right support later on, your elite Blitz core of cavalry will tear through virtually anything. This means that you'll need less units in the stack, and you'll have higher level units overall.
Re: Protective
Actually, I think that Japan benefits the most from the Protective trait, since protecting acquired cities cheaply is often a headache for other Aggressive civs who don't receive any bonuses for archers, and could be doing something better with those Swordsmen.
Japan can use cheaply made Archers with City Garrison II (!!) to protect its newly acquired holdings, and if that's not enough, it can build walls quickly in its new cities.
Once the Gunpowder Age Arrives, Japan's Gunpowder units enjoy the benefits of BOTH Aggressive AND Protective. Japanese Marines are fully capable of taking on Navy Seals and giving as good as they get. Similarly Japanese Riflemen are almost as good as Redcoats. Their Samurai, in fact, is almost a disappointment, since it's not all that much better than a normal Maceman, though the extra first strikes are nice.
Re: Imperialistic
Actually, I think that Julius Ceasar's Organized makes for the best combination with Imperialistic, since he can use Imperialistic to expand through whichever way seems best, and Organized helps him to keep the costs of a massive empire manageable. Making Settlers isn't weak if you're going to be doing it a whole darned lot, and +100% GG production is pretty spiffy if you know you can keep and profit from whatever land you manage to grab in the war.
If anything, I think Cathy is the weaker of the two, since her borders are still limited stictly by her tech, so there's a smaller limit as to what she can profitably acquire, and her Creative advantages peter out along with her Imperialist advantages mid game, leaving her with little to work with, whether in war or in peace.