There is a plan for a new demand model (probably going to be my primary focus next year, as it's a major update) to introduce city/nation ratings of 0-20 that will impact things like tourism and work travelers (the new model will split travelers into 7 different groups, each with their own preferences). If you'd like to help out, we do need to start compiling this data which is already in the database but unused (and all data currently sits at a default value).
The values I'm tracking are as follows:
Avg Personal Wealth
Income Inequality
Immigration Laws (How open a given country is)
Travel Appeal
Luxury Travel Appeal
Domestic Commercial Activity
International Commerce
These values are there for each nation and city, with the city rating being relative to the nation rating (so an average commerce rating in a city with high commerce will still have high commerce, the nation rating acts as a base level)