CommandoBob said:
@ControlFreak or Niklas or xyzy:
When you three look at swapping tiles between cities, how did you learn how to do this? What do you look for? Do you have a system or check list?
When I look at a city screen, I do not see the opportunities that all of you do.
The answer is "experience", probably. Lots of factors play a role: importance and purpose of the city, avoiding overflows, corruption levels, and sometimes choice. I sometimes use a checklist, especially this late in the game: I run through all cities once or twice per turnset, and write down all that need attention. Early in the game I usually run through all cities every turn. Even then a checklist is sometimes handy, so that you don't have to figure out the same thing twice.
Some decision points for tile management and swapping:
I check whether the city is fully corrupt or not. This is always immediately clear, except when it's close to fully corrupt, then it takes some experimenting: try to maximize shields or commerce, see if you can get more than 1. CivAssist2 will also tell you about corruption.
If the city is fully corrupt, then only food matters, so I ignore shield and commerce values of a tile. When this city is sharing tiles with another city that's not fully corrupt, then usually all good tiles go to that other city. Of course there may be exceptions, for example the corrupt city may get some good food tiles to hire a lot of scientists (specialist city), or it may get another good tile if the other city doesn't need it. I usually stabilize a specialist city (0 food surplus).
I try to avoid overflows of food and shields. Here a checklist is good, because sometimes this means: do 8 shields per turn for 2 turns, then 7 for 3 turns, etc. When the city grows, it can get pretty complicated to avoid shield overrruns on expensive builds. Occasionally you can trade in the overrun for extra commerce, for example by switching from a mined grass to a coastal tile (lose shield and possibly food, gain commerce).
Sometimes one city is just more important than another, and so will get priority on good tiles. For example a city building a wonder usually gets first choice in production tiles. In our case, Sages would get first choice in commerce tiles because it has Copernicus and (soon) Newton.
Sometimes you can effectively lower corruption by tile swaps. For example, suppose two cities are sharing a mined bonus grass and a mined grass, each getting one of these tiles. If the city with the bonus tile loses the extra shield to corruption, then swapping might help.
Later in the game it is usually a good idea to have food surplus at 0, 2 or 5, and shield production at a multiple of 10. If you are building large number of a particular unit, then other production levels may be good. For example, if your city is training 70 shield knights, then try to get it at 14 shields, not at 13 or 15. Early in the game this kind of thing is important with special purpose cities like settler factories, where food production and shield production have to match.
Let me give some examples from the 750AD save.
Our cities on Tadpole are all totally corrupt, stuck at 1 shield and 1 commerce per turn, and therefore will be specialist cities (with perhaps 1 round of settler production to fill in the gaps). That means: stabilize population (after settlers are done), and maximize the number of specialists. So how large should these cities be? Well, we don't want to build expensive aqueducts anywhere (they cost a lot of shields, and maintenance too), so cities on a river
could get to size 12, others to size 6 max. We also don't want to spend for happiness, so 12 may be a bit large. A tile producing 2 food per turn will only support the citizen working it. So the only tiles worth using are the ones making more than 2 food per turn, so that we can support science specialists. Golden Smurkz for example has access to floodplains and each floodplain does 4 food, after rails 5 food. So with 2 railed floodplains it will do 2 (city center) + 2*5 = 12 food, enough for 6 citizens, the 2 working the floodplains + 4 specialists. This is its maximal size anyway, so this seems the best plan. If we now look at Entremont, it's unhappy and it's using tiles producing less than 2 food, so it should not grow anymore. The city screen also show that it shares some tiles with Lamb on Broadway, a city that doesn't have any other good tiles to use. Entremont can hire 5 specialists, while producing 0 food surplus, and this will free up an irrigated lamb that can be used by Lamb on Broadway. If you start checking other cities on Tadpole, you'll see something can be done with Washington, with SF (in a few turns perhaps), with Lugdunum, with Atlanta, and with Richborough.
Now look at a noncorrupt cities, for example Carthage. It is size 6, it has an aqueduct, but it is not growing, for lack of food. It is also working an unmined grass tile, but switching to a mined one only increases waste, not production. Note that there is also a deer in Carthage's radius. It is currently in use by Smurkzala, also at size 6, but this city lacks an aqueduct and cannot grow. It is wasting 3 food per turn! So it doesn't even
need the deer tile, and can use one of the two hills instead. You'll see that the extra gold and 1 of the 2 extra shields from the saltpeter hill are lost, but the railed hill would add 2 shields, so let's take that one. Checking a bit more reveals that you can switch from a mined grass to a mined bonus grass, gaining another shield. We then have a choice to switch from the rock to the saltpeter hill. This will add a shield and lose a gold. I would do this (and rush 7 shields) because it speeds up the aqueduct and we need a lot of improvements still, but this is a choice.
Finally, Carthage now gets the deer instead of the unmined grass, gaining 2 food (the shield is lost). I then note we can switch from the forest to the hill to gain a shield, and that in 2 turns I could switch from the hill to a mined grass to speed growth at the expense of a shield (another choice, but probably a good one, because growth also means more production). Another choice at this point is to switch Zala from a mined grass to the forest that's now freed up. This puts it at food loss, but it gains a shield and will build the aqueduct in 7 without shortrushing 7 shields.
All in all we gained 2 food and 1 shield in Carthage, and transformed the 3 wasted food in Zala into 4 shields at the loss of 1 gold, with the choice of transforming another food into a shield.
Hope this helps.
.
. Please keep our units out of range of the Spanish as much as possible, and on rails (once we have them). Fortunately Spain doesn't show up with knights or muskets yet - or with their UU.
.
) But now Rails for Factory builds are 
Seatle and Boston each hire 2 more.
CAII now says I have 16beakers more than I should need. 
Anyway, I'll take the loss in food to save the 91g.
