Have you thought about agent based modeling/social simulation? It's not that clear from your question what exactly you're trying to achieve but ABM may be suitable for your purposes as it does lend itself to modelling human decision making as you can programme agents with different characteristics. It's also very good for spatial problems.
You could either use the data you have already gained on the population under study and use that to programme your agents and then you can forecast into the future and compare to what happens in the real life population. This can be repeatedly tested with different environmental factors say with an economic model on the decision to invest with the environmental effect of different tax rates. Alternatively you could set up a model and compare it to your real life data.
While chapter 26 of The R Book is on Simulation Models you may be better off with Netlogo than with R which is also free and especially designed for agent based modelling.
The Journal of Artificial Societies and Social Simulation is a great open source journal covering this area.