As it happens, the kingdom of Bhutan has been working on their constitution too lately (work in progress since 1972 to be exact...)
I am not too familiar with the whole story (wasn't even born back then), but it seems like the King voluntarily decided to start the transition from monarchy to "Democratic Constitutional Monarchy" that year, and what I find very fascinating is that they have managed to keep the document relatively short with a preamble which pledges sovereignty, liberty, justice, tranquility and happiness and well being of the people.
Granted, there is very little oil in Bhutan, and the country is largely homogeneous (thanks to a policy of busing a large parts of the Nepalese minority out of the country over the years), but not everything is rosy according to Mr Revkin's article (which you can find on a number of non-subscription pages, by copying the first sentence in NY Times and google it); political parties has yet to be formed for one... However, the document goes a long way in redefining the American constitutional concept of "pursuit of happiness".
There is a separate article on the environment, which states it is a fundamental duty of every citizen to contribute to the protection of natural environment and prevention of ecological degradation. There is also a separate article on "fundamental duties" that demands of the citizens to foster tolerance, mutual respect transcending religious, linguistic, regional or sectional diversities.
What has gotten everybody most excited is the provision
that the State should strive to promote pursuit of "Gross National Happiness" as opposed to Gross Domestic Product, and a policy of effort of the State to minimize inequalities of income, and concentration of wealth among citizens.
Leave it to the Buddhists...
And remember: "Medieval peasants worked less than you do"!