If you guys aren't using the CBP mod, you're doing it wrong.
bumping this after playing two games with it to say that the Community Balance Patch is pretty great. It changes a massive amount of stuff but I'll list some of the changes I found the most interesting:
-Unit trees are a bit more balanced, the Archer > Composite Bowman > etc tree actually stays ranged and there are proper units in between Crossbow and Gatling Gun and Frigate and Battleship now. Aluminum is slightly less all-encompassing late game as well (mid-late game siege units including Rocket Artillery use Iron now, and Modern Armor uses Oil).
-Tech tree is completely redone, you don't get Infantry right after GW Infantry with a no-brainer tech, and several lategame units like Mechanized Infantry and Stealth Bombers are now in positions where they're a lot more likely to be used.
-There's one semi-new unit line which is ranged mounted units and ends in the Helicopter Gunship (which now doesn't suck); the catch is that they only have one range by default so they're not completely broken like Camel Archers and Keshiks. Spear/Pikemen now promote to the same tree as Long/Swordsmen as well.
-Happiness is now based on "needs" of a city rather than just straight population; a city will want certain amounts of gold, culture, defense, etc based on population (and probably era) and if those needs aren't met, it generates unhappiness. The net effect is that happiness is less of a problem generally (unless you're going really wide/warmongering), it's next to impossible to eliminate unhappiness completely but dealing with unhappiness is now a lot more interactive than just building happiness buildings and buying luxuries.
-A certain number of policies is now needed for World Wonders, so Culture is harder to skimp on if you plan to get some. Also, the policy-based wonders now require you to have the full policy tree which is a welcome change.
-There's an "Optimize" button on the Great Work/Culture screen, and a "Swap and Optimize" one as well.
-Flat Coast/Ocean tiles are suboptimal, but not complete garbage now once you have the right buildings.
-Combat AI is improved and enemies will pull back damaged units instead of suiciding into you and move and attack with ranged units on the same turn. Newly founded cities and ones without defensive buildings will fall very quickly so you can punish weird forward settles more easily and city bombardment is generally a lot weaker. Also, melee units won't move off forts/citadels when attacking so they're much better for holding a position now.
-Most unique abilities/unit/buildings are either changed slightly (Assyria gets a one-time science boost if he can't steal tech on city capture) or completely redone (India gets an instant pantheon and then bonus growth/religious pressure for each follower, but can't create Missionaries) and generally stronger and more fun.
-Instead of bribing City-states for Influence, you now send them Diplomatic units that you have to build. This adds a geographical element to City-State diplomacy which is kind of nice, and Diplomatic units use a new strategic resource (Paper) that you get from specific diplomatic buildings, and which you can sell for some good money if you don't need it. The downside is that AI players on harder difficulties will use their increased production to spam diplomatic units like crazy (instead of with gold, where they seem to have a cap on how much they'll spend at once) and you'll see AIs with hundreds of influence regularly later on, so maintaining alliances with more than a handful of City-States is a lot more difficult.
-As a result of being better balanced, the game tends to actually be a fair amount harder, I played one Emperor and one Immortal game and they felt like Immortal and Deity respectively.
There are also a couple of things I'm iffy on (Artillery are kind of overpowered and not having Iron for them screws you over somewhat, trade value of resources is based on era and how much given AI needs them which is realistic and more balanced but makes trading kind of tedious especially since AIs will lowball you when you ask them how much something is worth, pretty significant amount of bugs) but overall I've really enjoyed it so far, would definitely recommend it if you're looking for something to inject new life into the game.
If you're looking to see more of what it's like without installing it, the series of videos I watched that got me really interested in it is