Peaster said:
I wonder if/when building on mountains is good strategy...? IMO you should rarely have to defend in SP games. So I never build on mts, and almost never on hills. Defense is much more important in MP/PBEM games.
I rarely build on mountains, but I love building on hills that are being mined.
Let see how your theory of interest applies here.
You get 2 food and 3 shields at city center. (3 food after supermarket and 4 shields after railroad.) Compare this to building on Plains where you get 2 food, one shield, and one arrow. (3 food after supermarket, 2 arrows in republic/democracy, and 3 arrows after superhighways.)
The food out put is the same. The trade off is 2-3 shields versus 1-3 arrows for an initial investment of 11 settler turns (1 to go on the hill and 10 to mine it). Using a 5% rate of return, the initial investment of settler time is equivalent to 22 shields. Again using 5% the trade off should pay 1.1 shields per turn. Equating 2 arrows to one shield the hill only loses after republic/democracy and before railraod by 0.2 arrows; otherwise it wins (by 0.8 or 1.8 arrows).
After Engineers, it takes only 6 turns (1 to go on the hill and 5 to mine) for a mined hill city making the initial investment only 12 shields, thus the trade off becomes even more worthwhile.
I should also point out that for cities with infrastructure the plains has an advantage in that improvements that increase arrow yield (library, marketplace, university, bank, ...) come about far sooner than improvements that increase shield yield (factory, power plant, and manufacturing center).
Last, but not the least, you get the extra defense bonus for the city on the hill. I do not know how to apply your theory of interest to this one.