I'd like to suggest that it might be an interesting idea to allow resources to be terminated prematurely.
This is only really viable assuming the resource areas remain with similar proportions to what they are now, as the only reason I'd like it is to remove some of my cotton plantations to allow me to replant with a better return, and better placement to allow more plantings. Cotton is currently the only resource area that is pretty easy to max out in terms of room, but still not be able to reach full potential under the purchase every 36 hour system.
The only problem I can see is that some people could abuse the system if implemented incorrectly, to essentially 're-roll' every resource to it's optimum return. HOWEVER, I'm not sure this would even be a concern for 2 reasons: 1) You'd still have to wait 36 hours between resource purchases, and 2) You'd still have to pay 50 geos for each resource purchase.
Thus, if you got a bad roll on diamonds say, you could terminate it immediately if you wanted, but you'd be out 50 geos, and have to wait 36 hours to try again. Since there is _always_ room for another diamond mine, why would you waste the geos by terminating it?
So, I think that this couldn't be abused effectively, and would only be worthwhile to use when your cotton area is physically maxed out. In that particular case, it would be nice to be able to remove your lowest income earner and try a new one, instead of having to pass up on planting at all.
I bring this up because I'm in this situation, maxed out at 18 plantations, and have had to pass up on purchasing more for over a week. My first plantation to expire doesn't do so until Dec. 1st.
Now, I wouldn't even care, except the whole point is that there is supposed to be a point in the long run to buying cotton every 36 hours, because it's supposed to be your biggest income earner from resources in the long run. As it is, it's really REALLY hard, if not impossible, to earn more from cotton than from oil. (Diamonds fluxuate above and below this line so much that it doesn't really matter)