Learn English – If living in the countryside is rural, what do you call living by the sea

Urbanization.

Or Population density. (Advantage: quantifiable)

The above are more often (perhaps exclusively) applied to a place rather than a person. That is, they are geographic terms, I understand you want a demographic term.

Great question. And timely as the world recently (2007) crossed into 50% urban. Some more ideas, with tongue half in cheek, for a single-word term:

• urbanity
• citification
• citizence
• citizensity

Okay I'll stop. The U.N. seems to call this demographic dimension "urban/rural".

I noticed during a elementary-school research project that kid happiness seemed to increase the further I drove from D.C. (the more rural direction of your spectrum). Also increased were noise and freedom and agedness of clothing and buildings.

Eudaemonia

(also eudemonia) a contented state of being happy and healthy and prosperous;a feeling of wellbeing and happiness (from GK.eu-, good + daimon, spirit)