Nishdog
Isolationist Bastard
If you are going to work on a micro-managable cultural expansion mod (as opposed to a random culture expansion which gravitates towards resources), then an option within the city management screen might be to set up a border expansion queue so that the cultural borders will automatically expand per your orders, so you don't have to manually choose how to expand each time border expansion occurs.
If going with a random border expansion system, maybe tie expansion into the city manager options aleady in the game: if you choose "Turn On Avoid Growth," then it won't rush towards that outlying wheat resource. If you turn on "Emphasize Production" then it will put more priority on acquiring the outlying copper resource as opposed to the adjacent corn resource. Well, you get the idea...
If going with a random border expansion system, maybe tie expansion into the city manager options aleady in the game: if you choose "Turn On Avoid Growth," then it won't rush towards that outlying wheat resource. If you turn on "Emphasize Production" then it will put more priority on acquiring the outlying copper resource as opposed to the adjacent corn resource. Well, you get the idea...